Peter Apian, a student of prominent astrologers at the University of Vienna, put practical astronomy on the map in a book he published in 1524, the Cosmographicus Liber. Before he attained a university position as a mathematician at the University of Ingolstadt in 1527, Apian earned his credentials as a printer of materials intended to chaperone stargazers as a type of field guide.1 To do this, he translated Ptolemaic cosmography into an observer-based pedagogy that he packaged into printed books. Academic cosmography was delivered via lectures to audiences of armchair astronomers who occasionally used visual aids in their classes. These took the form of metal and paper instruments meant for demonstration purposes and were largely theoretical in nature. By contrast, Apian’s update and visualization of the arcane genre into pictorially enhanced editions resurrected cosmography’s use for lay stargazers, whom he expected to make their own observations. Apian explained the rather abstract principles of mathematized geography via mechanical pictures, creating diagrams that centered individual viewers at the nexus of a world to be experienced firsthand and observed. Apian’s Cosmographicus Liber, printed by the cleric Johannes Weyssenburger in Landshut, simplified musty academic astronomy and attracted a broader public with the explanatory clarity of his diagrams.2 By way of visual and interactive volvelles with moving parts, Apian demonstrated principles of astronomy and mathematized geography to readers in a manner that could help them navigate the world. This chapter provides an art historical treatment of Apian’s work by way of his key mechanical images. It argues that Apian converted academic astronomy into prescriptions for viewing practices designed to school the user in making visual judgments. With visual tools that literally pop out of the book, Apian animated both the celestial and the terrestrial spheres. Apian’s Cosmographicus Liber, a book for learning to look at the heavens, strove to sharpen the eye of the literate stargazer.
This chapter treats observations as practices recommended for early modern night-sky exploration. According to Apian, the vault of the heavens was legible if one understood what one saw there. The author made self-conscious pitches to the reader about how to use vision to confirm the precepts of positional astronomy. This visual knowing, according to Apian, was an analytical category mediated by book illustrations. Objects on the canvas of the sky appear in Apian’s texts to be confirmed by observations, using pictures to visually verify phenomena on the horizon. By suggesting prompts for visual reasoning, this chapter argues, Apian instrumentalized observation as the tool for unlocking knowledge of the heavens.
In a dedication to the reader in a French translation of Peter Apian’s Cosmographie published in Paris in 1553, the editor alludes to the cosmography’s usefulness by specifically invoking its ability to present information to the reader’s eye:
Invoking the “naked eye” as the target of this cosmography’s design was not just a publisher’s idle pitch; it was a theme that had been developed by Peter Apian in the princeps of the Cosmographicus Liber and one that would be reprised in Apian’s other publications directed to a lay public. In fact, twenty years after the Cosmographicus Liber’s first edition, printers still advertised this as the book’s most marketable asset. Already from the date of its first printing in 1524 in the Bavarian town of Landshut, Apian appealed to the eye’s authority by picturing it frequently in the text. In so doing, Apian acknowledges it as an important agent for whose edification his book strives. The content Apian presented was hardly new; it was cribbed from multiple sources, some of which had been in circulation for centuries.4 Entirely novel, however, was Apian’s presentation of that data as visual templates for discoveries that readers in the field could make for themselves. This update amounted to a popular science for lay observers.
Apian’s Cosmographicus Liber is a manual of mathematical and astronomical geography that treats the basics of both astronomy and geography, breaking the discipline down into sections.5 Invoking Ptolemy in the headlining use of the word “cosmography,” Apian upheld the tradition of labeling Ptolemy’s geographic work as his fifteenth-century Florentine translator Jacopo d’Angelo had also done, recognizing the importance of Ptolemy’s work as one that mediated between geographic coordinates and the astronomical data from which those terrestrial coordinates were derived.6 Sixteenth-century editors of Ptolemaic data such as Apian referred to their efforts as cosmographic ones.7
To illustrate the aims of cosmography, Apian included a visual simile that sought to distinguish between geographic and chorographic levels of description active in cosmography by visualizing an analogy that most epitomizers of Ptolemy’s Geographia had overlooked, and possibly misinterpreted (Figures 2.1 and 2.2).8 Ptolemy had invoked the juggling act performed by the portraitist to explain this distinction between modes of describing. When rendering an entire head, the portraitist borrows the cognitive framework of the geographer when he contemplates the globe. The production of individual features, on the other hand, is analogous to the task of chorographic, or local, description.
2.1. Peter Apian, Cosmographicus Liber (Landshut: Weyssenburger, 1524), fol. 3.
2.2. Peter Apian, Cosmographicus Liber (Landshut: Weyssenburger,1524), fol. 4.
Apian was the first editor of Ptolemy’s work to pictorialize this conceit. With this image, Apian announced his book’s campaign to visualize the pedagogy of cosmography. In a woodcut consisting of four visual fields, Apian invoked these products of the portraitist: the rendering of the entire head compares favorably to geography’s pursuit to capture the macrocosm, whereas topographic description, or chorography, embodies the level of particular features.9 The illustration demonstrates these two ways to think about the terrestrial sphere, linking a globe to a head and a townscape to an ear and an eye. These images enshrined what might otherwise have been a couple of throwaway conclusions. The first point that Apian drove home was that the description of the earth could be translated into inherently visual terms; the second is that distinctions between incipient disciplines could be cultivated by informed observation. Apian was not only the first to recognize the visual potential of Ptolemy’s model, but also the first to formalize these principles of visual description as the modus operandi of his campaign to pictorialize cosmography.
The opening images of the eye and the ear in the Cosmographicus Liber have been frequently mobilized in the secondary literature; they are usually employed to showcase a dawning self-consciousness in early modern visual practice and the range of description suitable to rendering by a draftsman.10 But these images, significantly, are also the opening gambit of a text that goes beyond lip service to the eye’s role in knowing and describing. Rather than presenting just a handy mnemonic, Apian uses the visual analogy to pitch a claim with larger stakes, one with significant implications for the role of images in early modern scientific pursuits in general. The image provides the rationalization for understanding cosmography through picturing and, thus, underwrites the visual practices active in the book. The Cosmographicus Liber’s strategy for observing the world through visual means potentially revises the matrix in which the relationship between images and the development of popular science has been considered historically. Instead of simply supplementing understanding, images could also activate the observer’s eyes.
Apian studied in Leipzig and Vienna. After a brief sojourn in Landshut, he was summoned to Ingolstadt for a university post in mathematics in 1527, and it was here that he would establish his own print shop around 1525.11 As a printer, Apian speculated that privileging visual knowledge was a prerogative that the publishing market was uniquely capable of meeting. He guessed right. The Cosmographicus Liber was printed in Latin and in several vernacular tongues from 1524 until the seventeenth century, and the text even withstood Copernicus’s reconceptualization of the universe from a geocentric to a heliocentric model. An updated edition was released in Antwerp in 1529 with corrections by the Louvain mathematician and cartographer Rainer Gemma Frisius (1508–55).12 New additions by Gemma prompted another printing in 1533. Dutch and French vernaculars appeared shortly thereafter (Dutch in 1537; French in 1544). An almost continuous stream of Latin editions accompanied these new vernaculars. Before the end of the sixteenth century, there were at least forty-three editions in four languages.13 The vernacular editions must have seemed relatively risk-free transpositions of the original Latin to the printers, who surely based the logic of these wider offerings on the strength of Apian’s visual apparatus in conveying the book’s themes. Indeed, such synthetic astronomical content had never before circulated in vernaculars – as the subjects of astronomy and geography were restricted to university audiences and learned circles. To be sure, many contemporary books repackaged material already in circulation, but the manner in which Apian reconfigured his sources makes this book scarcely resemble any of its direct forebears.14 It was indebted to material from a number of significant sources of wide-ranging chronology: Ptolemy and Pliny as antique sources; Sacrobosco as medieval; more contemporary practitioners such as Regiomontanus and Martin Waldseemüller; and, later, Gemma Frisius. In fact, as Steven Vanden Broecke argues, it was only with Gemma’s enhancements to Apian’s Cosmographicus Liber that the book’s content elevated the status of cosmography in academic settings.15 Out of this admixture of old and new sources, Apian invented a popular science for lay observers. This chapter shows how Apian reformatted his major sources to configure the eye as the central agent of a pictorial guide to the heavens and the earth’s geography.
Images and Visual Literacy
Apian’s illustrations and instruments offer visual evidence that impacts two major scholarly trajectories: first, the development of scientific images; and second, the structuring of visual literacy. The historiography of scientific images has primarily been the province of the history of science, perhaps predictably, but more recently it has generated substantial interest from art history. Apian’s diagrams offer a productive reconciliation of these two fields. On the role of scientific images, this chapter proposes Apian’s instruments as consequential in shaping empirical practices that would themselves come to define new disciplinary approaches. On the topic of visual literacy, it aims to suggest that Apian’s program readied new audiences for the exercise of this skill.
Recent treatments of early modern epistemic, or knowledge-making, images track their role in the scientific revolution, and in a related area, the development of new disciplines of scholarly inquiry. These lines of academic investigation intersect with the history of printmaking at the juncture of the circulation and standardization of pictorial motifs.16 For both of these concerns, scholars have been particularly attentive to the fields of botany and anatomy.17 The emphasis on naturalism, along with its ahistorical accomplice “accuracy,” in early scholarship on the illustrated natural sciences skewed the attention toward the aesthetic accomplishments of illustrations in a few select fields. This emphasis had the further effect of alienating the treatment of images in the physical sciences whose illustrations were not naturalistically driven. This privileging of mimetic images by select fields, according to Renzo Baldasso, also bankrupted potentially more productive investigations of images’ epistemological functions.18 Mimetic concerns have been tempered in more recent studies, driving considerations toward the rhetorical claims of their media.19 Examinations of images’ conventions and non-unique qualities are also being offered over teleological celebrations of naturalism.20 More nuanced and historical applications of aesthetics in epistemic images have been tracked in astrological charts and horoscopes.21 Other efforts have tracked the role of images in guiding scientific practice, especially images considered to be operative in establishing new epistemologies.22 An important recent intervention has gone some distance to repair this void, considering a heterogeneous range of printed visual media to investigate their role in the formation of disciplinary sciences.23
Analyses of the historical reception of images has enabled more nuanced social histories of literacy. The work of images in shaping visual literacy has shifted from considering printed images as mere accompaniments to texts that were otherwise inscrutable to nonreaders to showing how they enlivened popular lay practices, such as devotion.24 Visual literacy has also been pursued by investigations of images to both reflect and shape a cognitive understanding of collective cultural values, a concept to which an influential study gave the term period eye.25 Studies of the synergy of words and images have emphasized scientific images’ efforts to serve as technical support where words failed.26 Images could also clarify for the reader opaque passages in the text.27 Some recent inquiries also foreground images’ functionality, such as those of technical images;28 or they have argued for them as a vital component of text technologies.29 Important work by Suzanne Karr Schmidt that features the reception of prints by early modern publics has given agency to these viewers as users – a claim that is backed by a surprising array of genres (including anatomical flap prints, devotional art, and movable dials) that stimulated interactivity.30 In a concurrent development, the rubric of epistemic images has been invoked to characterize the images’ internal pursuit of knowledge itself and explores the degree to which they toggle between representing and showing.31
This chapter bridges the themes of epistemic images and visual literacy by arguing that Apian’s cosmographic images raised new epistemological concerns for the reading public. The illustrations conspired to shape the visual literacy of a particular stratum of educated readership; Apian’s Cosmographicus Liber represents a coordinated effort to enhance readers’ ability to make visual decisions and sharpen their capacity to observe. Apian relied on popular knowledge as diverse as astrology, amateur navigation, and instructional manuals for scientific instruments, as well as more scholarly sources in astronomy and cosmography. Apian’s instruments embedded these forms of lay and learned knowledge into a pictorial program that aimed to facilitate new observational skills. The extent to which these images turned texts into a user’s guide can be measured in the next generation of printed books that adopted these images to prompt eyewitness investigations. Epistemic images mediated visual learning, enunciated new fields of inquiry, accompanied technical manuals, and thus helped establish new practices.32 My inquiry aims to contribute new scholarship on these knowledge-generating images and the investigation of the role of printed images in establishing new competencies in visual practices.33 Printed media directed the collaborative inquiry that underwrote new scientific disciplines, especially in their capacity to recommend and coordinate visual searches.
Updating the Ancients
In light of the proven strength of Apian’s visual program in the course of the long printing history of sixteenth-century cosmographic material, it is highly significant that the first visual analogy in the editio princeps already foreshadows the role that visual explanations will play in the illustrations that follow. Apian’s first step in transforming Ptolemaic content into empirical principles was to invite the viewer to make visual judgments. Instructed to use the book’s illustrations as a template for examining the stars, the viewer is asked by Apian to parse concepts such as cosmography and geography, marking these pursuits as distinct levels of epistemic engagement with the world.
Apian forecasts the guiding principle of his book as one of visual lessons, explicitly announced in the introduction, in which he says, “In these pictures, I will tell you what is meant by cosmography.”34 The isolated eye, as pictured here, is the sense organ with which Apian is most intently engaged, insofar as the eye is directly referenced by many of his diagrams, but, more importantly, by the extent to which the experience of cosmography is presented to a receptive ocular agent. The eye has literal agency for Apian. The book considers cosmography an art to be apprehended sensorily, as Tom Conley has convincingly shown, noting how Apian empowers the limbs of the vernacular reader, presenting body parts as “organs of locative perception.”35 Although he activates the observer’s anatomy in the spirit of do-it-yourself investigations, Apian positions the eye as the layperson’s antenna to unlocking material previously available only to those initiated in classical astronomical literature via the university. Destined for a broader lay public, which he attracted with the explanatory force of his visual diagrams, Apian’s text coached the layperson to access this information with his senses using his eye to measure, to gauge, and to observe. The extent to which Apian overhauls his source material by interactive demonstrations enabled by moving dials makes this text’s graphic conception and formatting a milestone in textual illustration and in the history of the book.36 The Cosmographicus Liber positioned illustrations to provide visual tools (both actual and conceptual) as the groundwork for empirical knowledge about the universe. Apian also made special claims for the role of the artist in capturing that empirical knowledge, evoking the artist in his explanation of chorography or topographic description: “Chorography is a complete and useful picture and no one other than a painter is able to do it.”37
Ptolemy’s Geographia circulated throughout the manuscript tradition in the form of instructions for making visual projections of the coordinates he treated, but its content throughout its manuscript career was transmitted by text alone. Apian capitalized on this paradox, charging himself with the task of visualizing Ptolemy’s principles. A set of images after the title page provides a conceptual introduction to cosmography, using an image of the eye at the base to tie the celestial and terrestrial spheres to each other (Figure 2.3). The adjacent illustration of a globe, a “detail” or fleshing out of the terrestrial sphere (including a continent labeled America), announces the interdisciplinary aims of the book and the ambitious plan to unite mathematical astronomy with geography. The lines that connect this pair of spheres show how information from the celestial sphere provides a basis for data for the terrestrial sphere.38 Apian sets the conceptual model into dialogue with representations of objects that have analogues in scientific tools, the world globe, and the armillary sphere. Apian’s image on the left can be seen as a type of exploded armillary sphere; perhaps more importantly, it is also a projection connected to a hypothetical viewer.
2.3. Peter Apian, Cosmographicus Liber (Landshut: Weyssenburger, 1524), fol. 2.
The apex of a set of rays resolves on the surface of a pictured eye. This image of an eye has been discussed as the source of omniscient vision belonging to God, a medieval view of God’s place as prime mover in a theologically formatted universe.39 This conceit depends on the framework of linear perspective to impart coherence to the visual model. Arguments for the tenacity of perspective in modeling the infinite, such as Erwin Panofsky’s, could logically underwrite readings of Apian’s eye as representing God’s point of view.40 Because the eye includes both the earth and the celestial sphere in its purview, as the perspectivist argument would go, it cannot belong to man.
But I would argue that this eye must belong to man, by virtue of another model of mathematized space also dependent on perspective: the projection.41 This type of perspective is not the kind that we detect in Renaissance panel painting, but it did govern certain types of scientific images. That Apian’s cosmographic model is imagining a planispheric projection (that situates man at the base) makes sense given the reciprocity cartographic projections are assumed to have had with linear perspective.42 Another visual mode from which Renaissance perspectival models might have taken their cues was architectural projection developed by engineers and theorists, whose designs may have facilitated the visualization of Ptolemy’s ideas into cartographic projections.43 Most theories of perspective’s origins agree on the importance of Ptolemy as a catalyst in the transition to perspectival projections. Ptolemy’s projection methods were intended to help readers conceptualize his observations.
Whether these prescriptions originated in cartographic or astronomic materials (which, as this chapter will show, were intimately related), Ptolemy serves as a linchpin for scholarly speculation on the origin of visual projections. Rather than in Ptolemy’s geographic works, however, other scholars find this origin in his theorizations of astronomic projections.44 The construction of a planisphere, according to Ptolemy, requires one to imagine the eye at the south pole; he envisions the equator as the picture plane for the planisphere. Onto this, he projects the tropics of Cancer and Capricorn and the ecliptic.45 Ptolemy’s strategy for planispheric projection, according to Kim Veltman, encompassed all the basic elements for linear perspective (an eye at a fixed point, a picture plane, and an object) and suggests itself as a compelling precedent for the type of abstractions on which linear perspective is built.46
Rather than representing the vision of God, it is more likely that Apian means to hail the human eye in this conceptualization of one’s visual cone. The resemblance these lines bear to rays depicted in optical models, as Steven Vanden Broecke asserts, also supports a reading of this as a human eye. The eye, for Apian, “centralizes perception as such.”47 Apian’s emphasis on the agency of human vision forges a new link in the realm of what was visually possible. Apian’s efforts to empower visual knowledge leave no doubt that it is our visual acuity that this book attempts to hone. A similar human eye also anchors the diagram on folio 110r, which shows the various phases of the waxing and waning moon (Figure 2.4). These moons surround the pictured eye like spokes on a wheel that align the sun’s light to what the eye takes in; the degrees of shading indicate portions of reflected light. The centralized eye tracks the face of the moon as it waxes and wanes through its cycle. Apian’s visualization of these perceptual complexities even extends to what the observer cannot see but should understand: the dark side of the moon. In this respect, the human eye can also function as an omniscient eye.
2.4. Moon phases, Peter Apian, Cosmographicus Liber (Landshut: Weyssenburger, 1524), fol. 110.
Inserting man’s eye as the primary receptor of cosmographic knowledge that connects both the heavenly and the earthly spheres pictured, Apian’s text represents an updating and visualizing of the data in Ptolemy’s Geographia. Apian’s aim is to make Ptolemy’s principles practical. He sizes Ptolemaic knowledge for the reader’s local coordinates. In so doing, Apian engages with his sources in a forthright way; his volume does not disguise his predecessors, but reconfigures their contributions in a way that is useful to the reader.48 Ptolemy as such had never been considered particularly useful to the academic curriculum; even when Ptolemy did make it into university syllabi, the Geographia did not lend itself to the structural commentary that was the modus operandi of university textbooks.49 The discipline of cosmography in the sixteenth century, therefore, seems to have developed outside the university and through the back door via the popular press and works such as the Cosmographicus Liber.50 More critical seemed to be the practical summaries of Ptolemaic learning in which astronomers trafficked in the medieval period. One of these was Sacrobosco’s De Sphaera – incidentally, one of the texts for which Apian was also plotting an overhaul.51
Although the demand for a synthetic text such as the Cosmographicus Liber seems like it should have been secure for a readership of amateur astronomers who recognized the advantage of illustrated and interactive editions, the market for popular astronomy was just getting off the ground.52 The bulk of information on astronomy proper had been tucked away in the realm of university learning for centuries.53 As a professional mathematician with a side job printing astrological pamphlets, or Practica, Apian must have gauged the spectrum of competencies in and appetites for digesting astronomical literature. This audience likely ranged from stargazers and geographers to monastics in charge of scheduling, or even physicians who were naturally linked to mathematicians through their common interest in astrology.54 For this diverse reading public, Apian clearly saw a market for crossover works like the Cosmographicus Liber, which might have been issued to supplement and clarify existing university texts, but he also updated older, more classical examples of the genre.55 At the time of the cosmography’s printing, Apian was also preoccupied with retooling the substance of one such manual, Sacrobosco’s De Sphaera. Our evidence for this is twofold: in the first place, the Cosmographicus Liber relies heavily on Sacrobosco as source material; and second, Apian would himself publish a new edition of De Sphaera in 1526, two years after the first printing of the Cosmographicus Liber. It is reasonable to assume that Apian developed the pictorial accompaniments for both his De Sphaera and Cosmographicus Liber in tandem. It is also therefore not surprising that for his own edition of Sacrobosco, Apian was primarily concerned with updating the visual apparatus of the text, given his sustained translation of astronomical and cosmographic thinking into pictorial formulae in the cosmography.
From the continuous popularity of Sacrobosco’s De Sphaera from 1220 through the sixteenth century, we can infer that many savvy fifteenth- and sixteenth-century printers saw the rewards of offering popular and vernacular editions.56 Repackaging information from Ptolemy’s Almagest and its Arabic commentaries, De Sphaera was one of the major sources of Ptolemaic cosmographic knowledge in late medieval and early modern Europe that explained the shape and apparent motion of heavenly bodies.57 It epitomized the portions of the Almagest that referred to earthly coordinates and incorporated the Arabic commentary on Ptolemy.58 De Sphaera was the most popular text on positional astronomy for use in academic instruction throughout the Middle Ages, but its circulation ballooned in the age of print, when it remained a popular manual for teaching astronomy in the university quadrivium.59 Illustrations aided the text’s many proofs about the relationship of the terrestrial to the celestial spheres and gave readers a conceptual model of cosmography.60 Sacrobosco, unlike Ptolemy himself, proved an excellent foundation on which to hang astronomical commentary.61 The editio princeps of De Sphaera appeared in either Ferrara or Venice in 1472 or 1473, and the text enjoyed a heavy traffic in reprints until the mid-seventeenth century.62 The advent of heliocentrism did little to disturb the useful nature of Sacrobosco’s text for practical navigation or instrument learning; it remained a vital source for astronomical knowledge even after Copernicus’s revised model of the solar system.63
Important developments in the pictorialization of astronomy texts that would influence Apian occurred in Erhard Ratdolt’s graphic laboratory. A Kalendario in which Regiomontanus’s corrected data met novel experiments in design was printed in Venice in 1476 by Ratdolt, followed by a color printing of Sacrobosco in 1482.64 These moves to streamline the graphic interface and to use color to help the reader discern differences in celestial phenomena show Ratdolt’s investment in visualization for the teaching of astronomy.65 Indeed, these experiments in color inaugurate a new emphasis on visualization in the history of printmaking: Ratdolt’s bicolor images of eclipses shown in black and yellow are generally considered to be the first woodcuts printed in color; he expanded such experiments in color printing several years later in Augsburg.66 Another important chapter in the pictorialization of Sacrobosco was begun by vernacular German editions printed from 1516 onwards, when De Sphaera received ample illustrations in recensions by the Nuremberg humanist Conrad Heinfogel.
Apian’s Cosmographicus Liber follows a tradition of visualization already gaining traction in the printed Sacrobosco editions, capitalizing on a major shift in the relationship between observation and scientific inquiry already being promulgated by these sources. Peter Barker and Kathleen Crowther have explored how this shift was mediated by images in their article “Training the Intelligent Eye,” which also provides a useful historiography of the role of images in natural knowledge in general. Even in the tradition of Sacrobosco’s tenacious models of spherical astronomy, empirical inquiry had been the prerequisite for the conceptualization of these abstract principles.67 Observation had always been a necessary component to conceptualization; it was reliance on observables such as the precession of certain planets that held the Ptolemaic model of epicycles and deferents together. Theoretical models were cooked up to explain what stargazers were seeing. Yet with these theories of planetary motion in place, there was little need for most students to leave their warm studies for chilly examinations of the heavens. With Sacrobosco and Peurbach, as the authors argue, the images grapple with explaining old theories.68 Images are prerequisites for users to form their mental conceptualizations.
While some early sixteenth-century designers of images for Sacrobosco’s De Sphaera considered the agency of the reader’s eye, it was not the focus of visual programs per se. Rather than commandeering the eye’s agency to certify a proof, celestial events were presented to the eye in terms of something an observer might have happened to notice. A typical example of the eye’s peripheral role can be found in Sacrobosco’s explanation of the spherical shape of the earth; the corollary he provides is of the sphericity of water on the earth’s surface. According to Sacrobosco, the shape of the earth’s surrounding layer of water can be inferred from the spherical shape of dew drops: from the homogenous properties of these drops, we can infer that bodies of water are also round.69 A supporting proof about the earth’s shape confirms this: when at sea, sailors atop a ship’s mast can spy a light on land not visible to those on deck. The visual impediment of the deck hands demonstrates the earth’s curvature.70 Some early printed editions tried to convey this parallax with woodcuts showing a square cutaway image of the water and a ship with lines drawn to shore (Figure 2.5).71 Although the idea of observation is implied by the proof, the accompanying illustration did not necessarily reinforce its demonstration as an empirical act. In Apian’s version of the De Sphaera, however, he positions observers at the ends of these projected lines, clarifying the proof via an outsized ship sailing on a sphere – literally a round earth that takes account of both ship and shore, picturing observers on the deck and atop the mast (Figure 2.6).72 Apian’s image reprises designs for editions of Sacrobosco printed in Venice in the late fifteenth century that feature the sightlines of the observers in the diagram, marking what they see as “visual rays” (Figure 2.7).73 The sightings modeled by the pictured observers were critical to the proof at hand – Crowther and Barker explain that such hybrids of diagrammatic and narrative images could be found in manuals designed explicitly for beginners.74 Deferring to visual strategies like these that attempted to clarify principles, Apian sought to foreground the aspect of the proof that was based on observational practice and pictorialized actual observers. Not far from Apian’s illustration appears another optical proof of the heaven’s corresponding roundness, and it describes the situation observed as analogous to how rays appear to bend in an atmosphere thicker than air. The illustration provides an example of the magnification of a coin through an aqueous medium (Figure 2.8) – at the receiving end is a disembodied eye that sees through the diffuse light. Eye guides such as this that taught the position of the eye in a diagram about observation have a precedent in sections of astronomical manuscripts devoted to measuring and gauging.75
2.5. Sacrobosco and Wenceslaus Fabri, Opus sphericum Johannis de sacro busto: figuris et p[er]utili co[m]mento illustratu[m] (Cologne: Quentell, 1501), 10r.
2.6. Sacrobosco, Sphaera Iani de Sacrobusto (Ingolstadt: Apian, 1526), 6v.
2.7. Sacrobosco, Sphaerae Mvndi Compendium Foeliciter Inchoat. … Iohannis de sacro busto sphæricum opusculum (Venice: Sanctis & Santritter, 1488), fol. 77.
2.8. Sacrobosco, Sphaera Iani de Sacrobusto (Ingolstadt: Apian, 1526), 5v.
Apian stages his demonstration of the earth’s curvature through a visual exercise (Figure 2.9). The image provides the reader with a menu of shapes against which to compare their observations of the moon’s surface during a lunar eclipse. By matching the geometry of the shape that appears on the lunar surface with options provided in his diagram, the reader can eliminate erroneous options. The earth’s projection of a sphere-shaped shadow confirms to an astute observer that the earth must be a sphere. This proof demonstrates how a finely tuned eye can visually verify evidence. To execute this proof visually, Apian indulged in a lengthy digression of pictorial counterproofs with redundancy built in. Apian’s full-page illustration enumerates a variety of other shapes that the earth’s shadow might assume when projected onto the lunar surface; these include a triangle, a square, and a hexagon.76 Apian used these differently shaped earths to caution his reader to rule out conditions that were not empirically verifiable. This explanation assumes good evidence to be observations that can or cannot be confirmed by the naked eye during eclipses, explicitly coaching the making of visual judgments. The sphericality of the earth enjoys incontrovertible proof when based on the empirical experience of an actual observer.77 This image records eyewitness observations, accompanied by caveats to rule out options that cannot be empirically supported.
2.9. Peter Apian, Cosmographicus Liber (Landshut: Weyssenburger, 1524), fol. 11.
Apian’s experiments with explanatory diagrams and such visual reiterations suggest that he developed the cosmography for readers for whom such proofs based on empirical experience seemed persuasive. Instead of the recursive bundles of resemblances and conveniences that characterized Michel Foucault’s explanations of causality in the premodern episteme, Apian’s empirically activated reader was empowered by books to settle for nothing less than visually verifiable truths.78 Illustrated guides to the heavens were proving increasingly useful to a broader stratum of the lay population in search of manuals to accompany their firsthand searches.
Mechanical Pictures for Observer-Centered Pedagogy
University lectures presented the basics of positional astronomy and frequently relied on various tools for their pedagogy. Apian trained in mathematical astrology in Leipzig and Vienna under Georg Tannstetter, whose own pedigree included Regiomontanus, Peurbach, and Andreas Stiborius – all of whose tenures were financed by imperial projects. The wall calendars and almanacs that resulted from these efforts expressed abstract designs and theories primarily intended for a group of university and court professionals. While many of his teachers’ efforts were in the service of explaining universals and updating tables, Apian instead envisioned a market that could unpack these trade secrets for the layperson.79 As a major strategy for popularizing basic astronomy for lay audiences, Apian converted narrative academic proofs into mechanical pictures, or volvelles, that centered observers by positing them as users. The earliest volvelles in printed literature appeared in the 1474 Nuremberg edition of Regiomontanus’s Calendarium and Erhard Ratdolt’s editions printed in Venice in 1476; these were also tools for gauging the movement of heavenly bodies.80 Printed volvelles embodied the premise of spherical astronomy and likely were intended to recall tools like armillary spheres that were a cornerstone of classroom instruction. Engagement with moving tools such as these spawned printed volvelles in works including Johannes Schöner’s Aequatorium Astronomicum (printed in Bamberg in 1521 and in Nuremberg in 1534), a work with which Apian was certainly in dialogue, and one that Suzanne Karr Schmidt cites as a precedent for Apian’s later horoscopic opus, the Astronomicum Caesareum (published in Ingolstadt in 1540).81 Apian likewise implemented complex moving paper dials and tools assembled from a variety of printed parts that translated the theoretical teachings of Sacrobosco into more practical information.82 With these, Apian could simplify his explanation of cosmographic principles. Placing man himself literally within the picture, Apian redirected astronomy away from principles and toward observer-centered pedagogy. For the spherical astronomy that Sacrobosco’s text served, little math was actually required – so it was the perfect text into which to insert observer-centered focus.83 Apian tweaks Sacrobosco to privilege the visual study of the viewer’s surroundings by articulating the observer as a recipient of sensory stimulus.
The relationship between the horizon and the zenith formed a major pillar of lay astronomy: the intersection of these lines centered the human observer. The zenith–horizon volvelle (Figure 2.10) anchored celestial circles to an earth-bound perspective. It encouraged the reader to envision the zenith as the extension of their head into space. Apian’s diagram teaches that the zenith is the pole of any observer’s horizon; the observer’s zenith is expressed in terms of the point it describes on the celestial meridian. The dial also aimed to show the relationship of the observer’s position to both their horizon and to their pole; and how the angular relationship between any observer’s zenith and their respective horizon is always preserved.84 Apian’s horizon volvelle incorporates the salient points of Sacrobosco’s textual proof, cuing the landmarks of spherical astronomy (such as the poles and the celestial circles) to adjustable earthly positions.85
2.10. Peter Apian, Cosmographicus Liber (Landshut: Weyssenburger, 1524), fol. 17.
The imaginary lines of the horizon and the zenith were important values for the amateur student of astronomy because they explained cosmographic truths in terms that could be confirmed visually. Circumscribed by the practitioner’s empirical experience, the horizon describes the portion of the globe that one can see. Apian’s dial consequently blocks from view the portion of the sphere that sinks beneath the horizon. The dial spins by way of a pointer fashioned as an earth-bound observer. By setting the figural index at the observer’s latitude, the dial reveals the horizon formed by that terrestrial circle. Thus, no matter what the latitude, the observer’s head remains at the center of a hemisphere articulated by what he is able to observe. The observer can also infer from this tool that their latitude is also equal to the altitude of the celestial pole. The fact that the hemisphere beneath the horizon remains hidden beneath the decorated space reinforces the idea of it as “that [line] which limits [one’s] vision.”86
The horizon also served as an important pedagogical benchmark for deriving latitude. Apian’s interactive dial converts Sacrobosco’s similes into coordinates of latitude that can help the user find geographic bearings in the world picture, providing an explanation that is easier to grasp than Sacrobosco’s original proposition.87 Apian’s reader is taught to convert the abstract lines of zenith and horizon into the practical value of latitude. The volvelle’s index, a figure of a man indicating his zenith, provides a stand-in for the user, to show how an observer’s latitude can be measured against the horizon and zenith. Apian’s dial extrapolates from Sacrobosco’s text practical knowledge useful to an amateur stargazer. Apian’s staging of this point through a demonstrative model follows what Steven Vanden Broecke claims marks an important shift to non-verbal visual thinking in the explanation of astronomy.88 The eye, whose intelligence Kathleen Crowther and Peter Barker argue was conditioned by the visual programs of astronomic texts that helped steer readers’ corporeal vision into inner mental visions of the cosmos’s order, becomes truly animated in Apian.89 The illustrations of the Cosmographicus Liber prioritized what the viewer could observe and assisted the mental visualizations necessary to grasp celestial motions within an observer-centered universe.
Apian’s Update of Sacrobosco’s De Sphaera
Sacrobosco’s text had weathered the generations fairly intact until its collision with Apian’s emphasis on pictorial learning. Recognizing the significance of his recent visual re-evaluations of Sacrobosco within the cosmography, Apian printed his own edition of De Sphaera in 1526, two years after the Cosmographicus Liber’s first printing.90 Apian, also the father of the portable “in octavo” editions of De Sphaera, significantly improved on the visual didactics found in most printed editions of Sacrobosco up to that date.91 As we have already seen in the example of the ship and the light on land (see Figure 2.6), for instance, Apian amplifies the triangular diagrams found in earlier editions of Sacrobosco to feature the more salient point that the water’s bulge must show the round earth that lay beneath it. Whereas Sacrobosco tells the entire story of astronomy through Euclidean geometry of spheres and intersecting lines, Apian’s repackaging imagines what these laws and propositions would look like to a roving agent.92 As with his Cosmographicus Liber, Apian’s update of Sacrobosco expanded on the existing cosmographic literature, hoping to clarify it through visual, and frequently interactive, demonstrations.
Apian’s volvelles and diagrams were popularized in his own Cosmographicus Liber as well as in editions of Sacrobosco that he printed for academic communities. Sacrobosco continued to be printed throughout the century, with many publications issuing from university towns such as Wittenberg. Aware of their didactic advantages, printers pirated Apian’s volvelles for their own mid-sixteenth-century editions of Sacrobosco’s De Sphaera.93 New volvelles were adapted from Apian’s Cosmographicus Liber, such as the one found in a Sphaera printed in 1538 in Wittenberg by Joseph Clug (Figure 2.11).94 Later editions, such as one printed in 1540, combined the teachings of volvelles that appeared separately in the source material.95 Integrating Apian’s zenith–horizon dial and the Organum Ptolomei, the user of Clug’s volvelle could set the horizon hemisphere to their latitude on top of a disc marked with lines of the sun’s declinations. The caption on the dial reads: “With this instrument, the roundness of the earth can be tested, followed by latitude. And it will be easier to judge all things which the author teaches about the artificial day in the third chapter.”96 Such declarations prompted the readers’ interaction with the dials.
2.11. Sacrobosco and Melanchthon, Ioannis De Sacrobusto Libellus, De Sphaera … (Wittenberg: Joseph Clug, 1538), fol. 31.
New objectives could be mapped onto these paper instruments, endorsing practices by printers eager to lend them an imprimatur of usefulness that served their own brand. “Nulla Dies Sine Linea,” or “No day without its line,” pleads the inscription on a volvelle in an edition of Sacrobosco printed in Wittenberg. With this motto, the printer advertised the celestial decoding that users could perform with the tool.97 This adage about daily routines popularized by Erasmus originated in Pliny’s commentary about the artist Apelles’s practice of daily drawing. It is mobilized here by the printer Joseph Clug to incite his readers to observe the daily linear path of the sun.98 The word linea frequently appears in Apian’s volvelles as demarcations of regions – on the Organum Ptolomei dial, for example – and perhaps that term also carried references to the threads themselves that accompanied dials as indicators throughout Apian’s oeuvre. Clug surely reprises the adage here not just to refer to the notional lines of the celestial sphere or planetary paths, but as an exhortation to readers to engage in artisanal operations – in other words, a note to the self about self-help. Clug’s semantic shift from the idea of “lines” from daily observances or routines to the “lines” of the sun’s path was received in a context where a concomitant change was occurring in the meaning of the word observation itself. Katherine Park and Gianna Pomata have pointed out how observationes transitioned in early modernity from connotations of regimens followed into a term explicitly signaling empirical practice.99 It seems that observation in both senses of the word converge in Clug’s volvelle: the dial’s motto inspires the user to make celestial observations a regular routine.100 The recycling of this hybrid volvelle throughout the century seems to confirm the growing popularity of the firsthand tracking of the sun’s path as a daily pastime for do-it-yourself observers.101
The transformation of academic astronomy into the subject of amateur investigation for “vernacular” viewers was achieved through the visualization of its principles. I would argue that the resurgence that the De Sphaera enjoyed in the sixteenth century came in large part from the potential that Apian saw in the visualization of spherical astronomy. We can say that Apian boosted future printings of Sacrobosco’s text on the strength of the popularity of their visual devices, which were borrowed from his cosmography. Vernacular editions of Sacrobosco’s material both laicized and energized observational practice. The vernacular Sphera Materialis edited and translated by Conrad Heinfogel in Nuremberg in 1516, already emphasized visual pedagogy.102 A reader’s annotations in the 1533 German edition of Sacrobosco’s Sphera Materialis: Eyn Anfang und Fundament der Astronomi suggest that this emphasis made an impact. That reader’s own drawings, which follow the foregoing Sacrobosco edition bound with other volumes at the Herzog August Bibliothek in Wolfenbüttel, include a featured eye.103 The illustrations on added manuscript pages indicate that the author tried to supplement textual content derived from Sacrobosco with images that expand the principles of spherical astronomy by mapping them onto the plates of a torquetum, an astronomical instrument that simulates the celestial sphere by featuring different coordinate systems on several movable plates. This reader’s pictorial supplement materializes the “material sphere” of Sacrobosco: an attempt to familiarize abstract principles by applying them to an actual instrument. While instruments such as the torquetum were designed to help the user envision the abstractions of spherical astronomy, this particular user seems to have been trying to facilitate comprehension of Sacrobosco’s principles by thinking them through with an instrument.
The vernacular Sphera Materialis edited and printed by Johannes Dryander in 1539 derived illustrations from Apian.104 While Dryander’s edition was an important contribution to the vernacularization of spherical and theoretical astronomy, such as in Waldseemüller’s Der Welt Kugel (printed by Grüninger in Strasbourg in 1509) and the Sacrobosco Sphaerae edited by Conrad Heinfogel, his was not prolifically illustrated. It was likely destined for a university audience, probably at Marburg, where Dryander occupied the chair in mathematics.105 But illustrations were becoming a priority for the popular editions of Sacrobosco, especially after Apian’s publication; Isabelle Pantin, for instance, notes the impact of Apian’s visual program on astronomy’s waxing pedagogical clarity.106 Whereas the marketing of Conrad Heinfogel’s German Sphaera Mundi in 1516 rested in part on the new vernacular translation from Latin, the title pages of the 1533 and 1539 editions explicitly advertised their contents as easier to understand because of the accompanying illustrations.107 These many recensions owe a debt to De Sphaera’s open design, a format that Matteo Valleriani claims was critical to Sacrobosco’s reception in the sixteenth century as a commentary useful for presenting practical mathematics for a number of fields.108
Perhaps this new enthusiasm for vernacular editions of De Sphaera can be attributed to astrology’s popularity in Wittenberg, where academic reforms by Lutherans were also afoot.109 Sacrobosco’s circulation within the local faculty was probably fed by intense interest in astrology and spurred by the reformer Philip Melanchthon’s own advocacy for popular astronomy.110 Just a few years after Apian’s edition, Melancthon penned an introduction for an edition of the De Sphaera (1531). Here, he articulated a reciprocal relationship between the observer’s eye and the practice of scanning the heavens for stars, suggesting that vision was particularly well suited to, if not explicitly designed for, astronomy.111 If the relevance of this thirteenth-century text was waning, sentiments like these reinvigorated Sacrobosco’s work and publishers attempted to boost sales with such hyperbole that linked the function of vision itself to the pursuit of amateur stargazing.112 Melanchthon’s suturing of the eyes to the stars was no doubt intended to elevate the importance of astronomy, but perhaps his comments were also prompted by the new publics of lay observers educated by the Cosmographicus Liber. Volvelles and diagrams derived from Apian’s cosmography came increasingly to define the profile and format of Ptolemaic recensions (such as Sacrobosco) produced in the wake of it.113 Diagrams derived from Apian also became a hallmark for many subsequent printings from the 1530s onward.114 Owen Gingerich notes that the moving dials became features adopted in most printing sites (including Paris, Antwerp, Cologne, and Venice) and the sine qua non of printed Sacroboscos from the 1540s onwards.115 Thus, the sixteenth-century reception of Ptolemy was greatly indebted to Apian’s visual apparatus for the Cosmographicus Liber.
Apian’s mechanical pictures as filtered through vernacular editions of De Sphaera ultimately made Sacrobosco a new locus for popular knowledge about the heavens. It is precisely in these updates to Sacrobosco that Matteo Valleriani locates a general trend of unifying diverse strains of study into early modern books that would become the sites of codified practical knowledge.116 That Sacrobosco would continue to be a mainstay in astronomic literature is clear from the many later publications, as well as the fact that significant debates about geocentrism would revolve around this publication as an authoritative source, including the 1611 commentary by the Jesuit Christopher Clavius, who would spearhead the Catholic Church’s resistance to Galileo.117 Printed beginning in 1570, the eight versions of the Clavius edition of Sacrobosco were no longer useful as practical guides to the heavens, as they were weighty and printed in larger formats. In place of Apian’s market-ready volvelles, they instead made room for propagandistic commentary in service of Jesuit science.118
Almost exactly contemporary with the vernacularization of Sacrobosco’s De Sphaera and its retrofitting with visual tools was the appearance of Apian’s Cosmographicus Liber in a number of vernacular editions, particularly Dutch and French volumes produced in Antwerp and Paris.119 It is perplexing, in light of these other versions, that Peter Apian seems never to have offered a German translation of the Cosmographicus Liber. Explanations for this could include the inability of Middle High German to handle scientific vocabulary, but many vernacular neologisms for spherical astronomy had been introduced by Conrad Heinfogel’s vernacular Sphera Materialis in 1516.120 Apian’s own trade in printed vernacular editions of instrument manuals for a wide readership may have also diverted the need for a German-language Cosmographicus Liber.121 I suspect that Apian never sensed a specialized market for a German vernacular edition of the Cosmographicus Liber in regions where the Latin version was already circulating – so confident was he that the pictures could carry his argument. He might have judged that amateur stargazers in academic and humanist circles were equally well served by the Latin, or any of the number of vernaculars circulating post-1537. Perhaps Apian’s preoccupation with other projects that likewise promoted the role of tools in the visualization of complex astronomic principles kept him too busy. Or he might have considered that a new vernacular Cosmographicus Liber would be a duplication of visualization efforts already underway in De Sphaera (1526) or the Cosmographiae Introductio (1529), and especially in his anticipated Instrument-Buch.
In any event, it is significant that Apian’s Instrument-Buch of 1533 delivered a synopsis of cosmographic principles formatted as a very visual how-to book.122 Apian explicitly designed this book with vernacular audiences in mind. The Instrument-Buch’s pictorial demonstrations would have served amateur astronomers and surveyors in an even more practical way than the Cosmographicus Liber itself.123 That Apian was cited in vernacular contexts provides evidence that his content was available among the burgeoning audience hungry for ways to develop their empirical experience of the world. Evidence of Apian’s role as a popularizer of astronomy can be seen in the contemporary manuals that introduced instruments such as the cross-staff and celestial globe and that invoked his name as an authority.124 Authors of printed practical mathematics still referred back to Apian’s Cosmographicus Liber for instructions on how to calibrate the eye in the night sky.
This last section has examined the dialogue between the Cosmographicus Liber and vernacular circulating astronomical texts in order to show how the theoretical content of spherical astronomy ceded its authority in the printed press to a growing visualized practice. Historians of science agree that not until the sixteenth century did Sacrobosco editions attempt to activate the hands and eyes of the astronomer; I would argue that much of this impetus to shape Sacrobosco into a useful text in the mid-1530s came from Apian’s visual engagement with those principles in the Cosmographicus Liber.125 While Apian was thoroughly steeped in updating Sacrobosco’s teachings for the 1526 Latin reprint he designed for university audiences, he simultaneously imagined the ways in which he could reshape the content for a learned but lay readership. Mechanical pictures not only helped locate a new audience for fusty academic knowledge, but these audiences also prompted a novel demand for spherical astronomy to be explained via interactive how-to volumes.
Exercising Observations
In tracking the premium placed by epistemic genres on the direct interface of observers with their environment, a milestone is marked by their self-conscious use of the term observation to characterize their searches. Such a turning point has been located in the appearance of the term (or some variation of the Latin verb observare or observatio) in the mid-sixteenth-century publication of astronomic material in Nuremberg. The rubric of Nachlass Observationes (1544) was invoked in the title of a volume that included a variety of visual samplings: the collected notes and coordinates of the astronomer George Peurbach, Regiomontanus’s treatise on astronomical instruments, and the weather observations of Bernard Walther and Johannes Werner. Historians of scientific observation hail Johannes Schöner’s use of Observationes in the title of his Scripta Clarissimi Mathematici M. Ionnis Regiomontani … Observationes XXX annorum a I. Regiomontano et B. Walthero Norimbergae habitae, a book that included treatises on astronomical instruments such as the astrolabe, torquetum, Ptolemaic regulum, and the cross-staff by Regiomontanus and George Peurbach.126 With the term observationes, Schöner, functioning as an editor here, indicated the idea of collective observing practices.127 While this term had previously signaled individual case studies, we might say that the shift in its use around the mid-sixteenth century to promote “collective empiricism” might have been the result of individual agency in practicing observations as pictorially developed by Apian’s Cosmographicus Liber.128 In fact, Apian was already using the term observatio in a pamphlet announcing the comet of 1532 as well as in the related Practica for that year.129 The degree to which both Schöner and Apian attended to the publication of their works with interactive diagrams and volvelles, and the fact that both of them resorted to self-publishing in order to more precisely supervise a printing process increasingly reliant on visual props, suggests a dialogue between them that went beyond the formal similarities of some of their astronomical publications.130 Their labors cultivated audiences for empirical experiences customized by the practice of observation.
At least one of the practical applications of systematic celestial observations arose at the point at which academic astronomy and astrology came together. Apian’s list of publications reflects the interpenetration of the two pursuits in early modernity and illuminates how their concerns were brought together within the publishing industry. In the age of print, it was inevitable that academic astronomy would meet the visual platform that was active in genres that did present useful information derived from celestial knowledge: astrology.
Celestial knowledge was the basis of astrology, a lay genre related to astronomy that traced the sun’s path through the zodiac in order to cue those movements to quotidian labor, health, hygiene, and aspirations for matrimonial bliss.131 Published data on the movements of celestial bodies circulated on a popular level in the form of almanacs, prognostications, and short pamphlets, typically of eight to ten leaves, called Practica.132 In addition to other topics, these books suggested propitious times for daily activities based on knowledge of the heavens. Many seasonal practices such as bathing, cupping, and venesection were scheduled by astrological observations; the published recommendations for these routines were generated by mathematicians.133 Apian’s publishing activity spanned lay genres such as astrology and more academic astronomy, and thus promoted cross-fertilization between the pictorialized cosmographic publications and the vernacular literature on prophecies and prognostications.
Apian’s own roots in practical mathematics served his busy program of printing vernacular astrological pamphlets. The annual lunar calendars and predictions that Apian printed beginning in 1523 as Practica financed his more scholarly ventures.134 Seasonal almanacs that predicted weather, Practica also speculated on the outcomes of wars, public health hazards, and the success of harvests. Eclipse schedules in Apian’s Practica followed the design of those found in contemporary calendars.135 Perhaps it was Apian’s attention to the needs of local astrologers, physicians, and weather watchers that fed his conviction that Ptolemy need not be the first and last word in astronomical texts. Instead, Apian emphasized in these publications how observations obtained with modern instrumentation could serve useful ends.136 Such pragmatic needs were also serviced by the wide array of Practica (including almanacs and “weather books”) marketed to a growing audience of practitioners. In both their address to readers and their title page illustrations featuring farmers and peasants, these books were among the first that hailed a broad cross-section of social classes as reading publics of lay learners.137
Ambitions to serve markets for both academic and popular literature in Apian’s press probably guided his fashioning of the Cosmographicus Liber into a perfect text to reach crossover audiences – it borrowed images from academic astronomy texts, but it was also clearly indebted to the practical demands of astrological publications.138 Schedules of lunar phases and eclipses inspired by Regiomontanus’s Calendaria also appeared in the Cosmographicus Liber. Apian’s version of such a calendar showed an approximately fifty-year schedule of eclipses relating to specific coordinates on the globe (in this case, the coordinates of Apian’s hometown of Leisnig in Saxony). Such data mimicked that found in local astrological publications. While academic texts on spherical astronomy did publish images of lunar phases, how, one might ask, was such data pertaining to local coordinates such as Leisnig actually useful to readers of theoretical astronomy? The cosmography’s lunar calendar took a middle ground: this schedule was a theoretical model with practical applications. In the context of the Cosmographicus Liber, it was one of two methods Apian presented to help determine one’s location. The eclipse times shown for Leisnig provided the prospective observer with a reference meridian and time. If observers could time the eclipse at their local coordinates, they could then calculate the time difference between Leisnig and their own locations. Converting this to an angular measure would produce a longitude reading.
A more practical way of deriving longitude involved tracking the motion of the moon relative to a fixed star, a technique employed by mariners in celestial navigation. This strategy elaborated on the lunar distance method publicized by the Nuremberg mathematician and astronomer Johannes Werner in an edition of the Geography printed in 1514. Apian’s text coupled instructions on how to obtain these values through the use of a simple instrument, a section introduced on folio 30 as the Use of the Cross-Staff (Figure 2.12), and followed by an illustration that explained how to make and deploy such an instrument. With it, one could determine the elevation of an object above the horizon, or measure the angles between two celestial features.139
2.12. Peter Apian, Cosmographicus Liber (Landshut: Weyssenburger, 1524), fol. 32.
Apian’s cross-staff illustration can be seen as a hybrid model with both narrative and diagrammatic components. This tripartite woodcut shows principles that governed the cross-staff’s production, including the angular scale by which it should be calibrated, a depiction of an actual observer using it to measure the angle between the moon and a star, and, lastly, a demonstration of its application on earth by a user.140 The pedagogical value of Apian’s three images together clearly outstrips the narrative explanation offered by the text itself.141
One of the challenges facing the non-specialist researching the secondary literature of early modern scientific instruments is that their use, calibration, and purpose are never presented in a predictable or pedagogically clear order. Furthermore, explanations are typically vague about which quantities are already known or required in order to use them. This stands in stark contrast to some relatively complete early modern explanations. Apian’s illustration aims to clearly deliver instructions for the proper calibration and use of the cross-staff as related aspects. For this reason, his illustrations are vastly more informative than many later ones. They pictorialize the purpose and use of instruments and often show methods and results of observations made using them.
As the illustration at the base of the image shows, the staff was supported just under the eye to sight both the moon and a nearby star. The user then slid a movable cross-piece until it spanned the distance between two points; the reading taken from the staff would show the angle of separation. The device should be calibrated via a scale shown in the left-hand woodcut.142 Instead of showing how to hold the staff itself, the illustration in Apian’s princeps simply floats the staff before a pictured eye.143 Lack of instructions was perceived as a shortcoming that was rectified in Apian’s later editions, as he increasingly came to see the job of images to be to assist the user in the field. Apian retooled his images around the needs of a prospective user: in many practical publications that would follow the Cosmographicus Liber, he would feature practitioners in the field using the instruments he recommended in the text. Apian would continue to publish pamphlets for amateur observers of the heavens, sometimes in the context of Practica, and sometimes in pamphlets devoted to a particular celestial event. In Ein kurtzer bericht der Observation unnd urtels des jüngst erschinnen Cometen… dises XXXII. Jars (printed in 1532), a title page image shows a comet blazing across the sky viewed by a pictured observer who tracks its position against reference stars with a cross-staff (Figure 2.13).144 Illustrations of the path of the sun against a backdrop of the zodiac band, as well as dates of his observations, appear in both this publication and an almanac Apian printed that same year, Practica auff das 1532. Jar. In these two publications, we see echoes of both the methodology and the pictorial apparatus of the Cosmographicus Liber constructing the foundation for Apian’s future visual programs for his vernacular spinoffs. Significantly, we also see the term observation creeping into these titles and providing the justification for the publication. In both of these works on the comet, Apian clamors repeatedly for observational acuity that underwrites the rigorous training of the astronomer. Even in the more astrologically oriented text of the Practica auff das 1532. Jar, Apian announces himself as an astronomer whose assiduous observations ensure the precision of his predictions. Such visual explanations of instruments for amateur stargazers would reach an apogee in a publication designed around the use of instruments, Instrument-Buch (1533). These works conspired to turn the products of university astronomers into more practical field guides.
2.13. Peter Apian, Ein kurtzer bericht der Observation unnd urtels des jüngst erschinnen Cometen jm Weinmon vnd Wintermon dises XXXII. Jars (Ingolstadt: Apian, 1532).
Period advancements in determining longitude through both the eclipse and the lunar distance method have not been properly credited to Apian’s relatively clear diagrams, according to Uta Lindgren, who also believes that these illustrations’ alleged purposes are masked by captions that dilute their true contributions.145 The chapter of the Cosmographicus Liber preceding the diagram announces the Usus Baculi or the “use of the cross-staff” (fol. 30). According to Lindgren, this title does not go far enough to highlight the device’s more significant contribution as a means of calculating longitude – a purpose that is unequivocally announced in the text that follows the subject heading. The image of observers placed at some distance from one another serves as an explanation of longitude; the difference between their respective angles of vision is equivalent to their difference in longitude.146 The word differentia found in later printings of the woodcut, according to Lindgren, indicates the difference in degree between the moon and the fixed star at the observer’s locations. Apian’s pedagogy not only coached readers to make their own observations, but it also taught the principle that observations were relative to their observers.
This lesson was adopted by later publications that extrapolated from these principles. The Louvain mathematician Gemma Frisius has often been considered a student of Apian’s because of his long engagement with Apian’s texts as his editor. Gemma spurred the printing of the Cosmographicus Liber in the Antwerp press, frequently padding those editions with his own notes and amendments. One popular addition were charts that would enable longitude to be found via the lunar distance method. This entailed providing data of the relative positions of moon and stars. To find longitude via the lunar distance method, data points obtained must be read against a table of relative positions of the moon to the stars, such as those enumerated in Regiomontanus’s Ephemeridies.147 Later editions of the Cosmographicus Liber also include a chart inserted by Gemma that details the positions of fourteen stars near the ecliptic that can be used to calculate the moon’s position. Such data had already been presented in novel visualized formats in contemporary print productions. Johannes Stabius’s wall chart Astrolabium imperatorium (1515) offered an aesthetic presentation of the diurnal location of the sun and also the position of ten bright stars.148 A compelling graphic presentation of the stellar positions, according to Richard Kremer, was Stabius’s most important contribution to mathematical astronomy.149 Kremer argues that the coordinates rendered by this device, a geometrical tool without moving parts, were explicitly conceived so that the viewer could simply consult the device as a visual model, rather than as a conceptual one. It cleverly displayed, rather than proved, and thus encouraged new types of cognition. Apian embedded demonstrations of celestial data collecting in short sections labeled with explanatory chapter titles and images that illustrated how to perform these tasks, balancing practical application with more theoretical objectives.
Although the first textual mention of the cross-staff surfaced c. 1342 in the context of surveying and astronomy, its use in the sixteenth century by mariners and navigators was surely expedited by Apian’s clear explanations. Apian geared his tools toward the amateur who could now attempt personal celestial observations. Graphically embedding visual demonstrations within the explanatory text, Apian designed the Cosmographicus Liber to instruct amateur astronomers to gather observations. With this objective, Apian’s work inspired a generation of practical publications, primarily spearheaded by Gemma Frisius. With this practical agenda, Frisius’s works differed from those of his French counterpart Oronce Fine, whose emphasis was on theoretical practical mathematics.150 Gemma Frisius’s corrections and additions to editions after 1529 made Apian’s cosmography even more versatile for a class of professional observers such as surveyors. Sections on surveying added by Gemma came with diagrams and appeared as an appendix entitled Libellus de Locorum describendorum ratione in the editions printed in Antwerp beginning in 1533, with a reprint by Arnold Birckman and Johannes Graepheus.151 In later Antwerp editions, these sections are accompanied by woodcuts of surveyors armed with the cross-staff measuring angles they could see but not reach. That readers were developing a new useful position vis-à-vis the text can be seen in a copy preserved at the Museum Plantin-Moretus into which the owner directed the book binder to insert periodic gatherings of blank pages. Clearly, this patron added extra pages to enable commentary on the text. The comments by the owner here include marginal synopses of the text’s discussion, principles of geography distilled into a list of twenty-two points, observations about eclipses, and a drawing of a hand whose fingers form a didactic model of the climate zones.152 Gemma’s amendments to Apian would go on to serve a community of non-academics such as surveyors, architects, and builders who needed to make use of such angular measurements for their calculations.153 Vernacular editions from 1561 feature Gemma’s tools, such as the sea-compass, in their titles.154 Practical knowledge about how a compass might have been used for navigation would certainly have been of interest for the reader/viewers Apian developed: a community of mathematical amateurs.155
Enabling Empiricism
Another form of data collection Apian popularized was finding the time at night. That Apian’s cosmography was being sought for these practical aspects is suggested by a brief table of contents in the 1561 Dutch edition that lists finding the “hour of the night via the stars” to be the third most noteworthy feature of the book. The nocturnal dial needed for this was used principally by mariners whose time readings enabled them to stay on course in their latitudes and to predict the tides.156 Other segments of the populace who could profit from readings of nocturnal time were astrologers producing horoscopes, or monastic communities in charge of scheduling prayers, chants, and other rituals.157 A nocturnal dial determines the time at night, just as sundials mark the hour during the day. The last few pages of Apian’s 1524 edition were devoted to the explanation of the nocturnal (Figure 2.14), explaining the principles, theory, and use of the dial. One page even provided a model of the instrument itself.158
2.14. Peter Apian, Cosmographicus Liber (Landshut: Weyssenburger, 1524), appendix, fol. 109.
Apian both illustrates the theoretical model of the nocturnal dial and provides one that could be used to find the time by sighting Polaris through the center and then aligning the arm to the reference stars (Figure 2.15). Over successive pages, he illustrates a user employing the tool to find the angle between the pole star and the reference star; lastly, he includes a page that contains a model of the dial and a pointer arm, presumably to be cut out and attached to firm backing and a stick. Most of these seem to have been printed on or glued to sturdier parchment and tipped into the manual.159 Once the instrument was detached from the book, it either could have been used in the field in a rudimentary way or could be manipulated alongside the book for better comprehension of the actual tool’s workings.160 These explanations showed how to make use of local coordinates for telling the time and to help stargazers orient themselves. Tools like these would form the focus of Apian’s guides to a variety of instruments (such as ones on quadrants and dials) published in the 1530s, including the Instrument-Buch that established the foundation for the observations of Tycho Brahe, for instance, whose attention to description and use of instrumentation were key in formulating a working model of the universe.161
2.15. Peter Apian, nocturnal parts in Cosmographicus Liber (Landshut: Weyssenburger, 1524), appendix, fol. 110.
A lunar instrument, the Instrumentum Noctis (Figure 2.16), was more of a theoretical volvelle than the nocturnal dial, but one whose elegance was predicated on stunning design. It appears in the appendix to the Cosmographicus Liber along with Apian’s disclaimer that it was designed at the behest of his brother Georg. Using two moving plates, to each of which a pointer is attached, one should be able to derive the time at night. A lower plate carries a design made from an algorithmic projection that simulates the moon’s changing phases through an opening in the circular plate. Apian’s text explains that the pointer of one dial is set to the altitude of the moon; the other dial, with the circular window, should be squared to the moon’s phase. Together, these two dials point to a number that renders the time at night. The dial derives useful data from the observation of the moon’s phase: the reflected light seen on the lunar surface is a measurement of the relative angle between the moon and the sun. Coupling this with a measurement of the moon’s altitude provides the location of the sun. The time at night can thus be inferred by triangulating the position of the sun beneath the horizon.162 This data point renders a value more useful to the viewer: the time at night. This value could be used for scheduling events, predicting eclipses, making horoscopes, or simply estimating the number of daylight hours. Apian’s stargazers would also have found the lunar volvelle admirable for its elegance in design and the way it synthesized the clockwork of the heavens with just a few moving parts.
2.16. Peter Apian, nocturnal instrument in Cosmographicus Liber (Landshut: Weyssenburger, 1524), appendix, fol. 106.
Paper instruments could also pictorially synthesize theoretical astronomic propositions. With another moving paper volvelle, readers could derive practical values from complex Ptolemaic concepts. This dial found on folio 24 revives the Organum Ptolemei (Figure 2.17), a disc with a projection of the sun’s declination and the hours. It was a tool that astronomers over the centuries had tried to reconstruct from Ptolemy’s prescriptions.163 While reports about the Organum Ptolemei proliferate in manuscript sources, Apian’s might actually be an early attempt to create one in paper.164
2.17. Peter Apian, Cosmographicus Liber (Landshut: Weyssenburger, 1524), fol. 24.
Apian’s version of the Ptolemaic instrument is comprised of three movable parts mounted atop a disc with latitude markings. The components include a rectangle representing the horizon; a rotating triangle called Trigonus marked with the line of shadow that would be cast by the sun; and a rotating disc with a grid of morning and afternoon hours bordered by the zodiac band. The cylindrical grid printed on this disc is an orthographic projection of the equinoctial (colure); it offers a schema that reconciled the parallels of the celestial sphere to the plane of the equator.165
The instrument’s functionality was loosely explained by the ten propositions that precede it in the text. With the instrument, it is possible to calculate one’s latitude and the position of the sun in the house of the zodiac, derive the height of the celestial pole from the altitude of the sun (via the triangle activated as a shadow vane), and also determine the height of the pole star. Furthermore, one could derive the time of day in the same way as one might employ a sundial; establish the time of sunrise and sunset; measure the length of unequal hours of days and nights; and lastly, determine the height of the sun on cloudy days.
Users are instructed by Apian how to set the dials. The user would align the horizon bar to the appropriate latitude and set the index pointer of the large disc in the marked quadrant to the height of the pole star. While the dials are meant primarily to demonstrate principles, at least two of the propositions suggest that the parts could work in concert to enable empirical investigations. Once the user’s latitude was entered in the Organum Ptolemei, “the intersection of the triangle with the grid of parallel and hour lines on the rotating disc works like an equatorial sundial, while the intersection of the horizon line with this grid can easily be related to the set-up of a horizontal sundial.”166 While the tool mimics the principles of the sundial in this way, Apian expanded the dial’s practical operations. He layered both practical ends and theoretical didactics onto the dial.167
A sundial was a purely practical tool designed to measure time from readings of the sun’s altitude at specific locations, and it was tied to those specific locations. By contrast, Apian’s instrument can be used for determining the length of daylight hours for a given latitude, enabling the user to calculate the length of the day or night at any location and at any time of year. From these values, the user could generate new data, such as measuring fluctuations in daylight hours over the seasons. While information about local daylight hours could also be found in almanacs and calendar pamphlets, this tool could help derive data that was handy for cuing regimens to the length of the day at specific times of the year.168 From practical calendaria, the reader could schedule precise dates for activities such as planting, harvesting, healing, and distilling. But Apian’s tool is in fact more useful than these purely practical aids, argues Vanden Broecke, because it clarifies the operation of a sundial by mapping astronomic data onto terrestrial coordinates that could be visualized.169 By demonstrating principles of the empirical processes by which that data was derived, the Organum Ptolemei enabled the reader to translate theoretical knowledge into more practical applications.
By synthesizing data from observations gathered over time, this tool could demonstrate variance in the length of daylight hours over seasons. These were data points that amateur observers had little chance of grasping in the absence of regular and sustained investigations. In this way, we can think of the Organum Ptolemei as a calculator of real values for a series of variables, such as how to divide the day up into hours of daylight. It is thus a tool that replicated a phenomenon that could be observed, and it gave the reader a purchase on the observable world. It taught the reader how to turn observations into practical knowledge.
The tool could illuminate other astronomical phenomena that could be inferred from observations. On the movable triangle marked Trigonus, there is a boundary line marked Linea Umbrae; this refers to the line of shadow that would supposedly be cast by the instrument. But another function can be inferred from it beyond its function as a pop-up shadow vane: the Terminus could also have potentially suggested to the viewer the boundary between light and darkness. This line might also represent the threshold of light and darkness, that boundary, or terminator, that we witness in air travel today, but one that could only be inferred in Apian’s day.170 Apian’s tool aims to help conceptualize a phenomenon that, at least in principle, should be observable. Imagined here as a visual exercise, this terminator between night and day was surely a theoretical notion in this period, but one derived from the data of collective observations.
While the experts still disagree about the precise practical applications of the complex Organum Ptolemei, most would concur that this volvelle had an enormously influential afterlife. The volvelle’s capacity to direct do-it-yourself activity can be seen in subsequent printings of other astronomic material. Versions of the volvelle surface regularly in later editions of Sacrobosco’s De Sphaera, in which, we will remember, it became a critical feature of the afterlife of that text in the sixteenth-century printed editions.171 It should also be noted that, at this point, Apian’s volvelles find their way back home into more academic contexts – indeed, Gingerich calls these Sacrobosco editions the first true ancestors of modern astronomy textbooks. Steven Vanden Broecke argues convincingly for how Apian’s illustrations rewire the practice of cosmography by prioritizing visual learning; he argues that these tools “technologized” cosmography, making it mechanical and useful.172 This knowledge also helped to make celestial events foreseeable. On the road to shaping a more predictable universe, Apian’s instruments required users’ input, incentivized empirical engagement with the world, helped sharpen their observational acuity, and created expectations of visual verifiability.
The goal of informed peerings into the heavens under the rubric of cosmography was to bring astronomy down to earth. Apian’s cosmography ripened in the age of geographic discovery and paralleled empirical developments in that field. In addition to astronomy, the other discipline to which sixteenth-century cosmography was indebted was geography, a field whose practice was simultaneously being overhauled by empirical experience in cartography. New knowledge was made possible by firsthand reports of data confirmed by navigational techniques and data recording enabled by instrumentation. This synergy displaced old coordinates and plotted new ones. Apian established cosmography as a genre that bridged the disciplinary divides between astronomy and geography. To be sure, the second-century AD Alexandrian Ptolemy himself had envisioned cosmography in this way. Ptolemy’s intention was to furnish the Geography with maps, but these were never transmitted along with the projection methods and the data. Despite Ptolemy’s original vision, astronomy and geography had essentially remained discrete pursuits in the scribal tradition.
Travel accounts printed in Latin and in vernacular languages were profuse enough by the 1480s to be collected by publishers in anthology format in the early 1500s. Their rapid furnishing with visual accompaniment brought new credibility to the eyewitness when those claims were backed by empirical experience suggested by images. One of the first important syntheses of empirically derived data sourced from travelers occurred in a cartographic think-tank located in St. Dié in present-day Alsace. Chief among those amendments made to geography was the incorporation of the Americas into existing models of the globe. These developments in the visualization of these “discoveries” (as Europeans understood them) took place against the backdrop of the Ptolemaic world picture and were specifically registered in the St. Dié workshop as revisions made on empirical grounds. Ptolemaic cartography was challenged by new facts whose novelty was accompanied by a self-conscious embrace of instruments and technology. The geographical revisions made at St. Dié reached their widest audiences via the circulation of newly drawn maps – it can be argued that the strikingly visual impact of these revisions underwrote the success of their conclusions. Therefore, it is not surprising that Apian, whose graphic projects were already heavily invested in the display and use of instrumentation, purposefully cribbed the cartographic novelties from St. Dié as a foundation for the second half of the Cosmographicus Liber. This appropriation can be interpreted as Apian’s kindred pursuit of evidence derived from instrumentation and empirical inquiry.
Apian’s geographic pictures and Gemma Frisius’s maps that would later accompany editions of Cosmographicus Liber are among those that helped broadcast the cartographic knowledge developed in the St. Dié workshop. As Apian illustrates at the beginning of the Cosmographicus Liber, geography and astronomy supported the intellectual weight of cosmography in equal measure. The text’s entire second half aimed to incorporate geography’s new developments, following the dictates of a slim volume from St. Dié that was also engaged with contemporary advancements in instrumentation and data collecting. Incidentally, this volume also bore the word “cosmography” in its title. Edited by Matthias Ringmann and including maps made by cartographer Martin Waldseemüller, the Cosmographiae Introductio (1507) was a pamphlet dedicated to the Emperor Maximilian that included Amerigo Vespucci’s reports of travels to the Americas and was intended to provide commentary to an accompanying map.173 In addition to this world map, the workshop also printed gores for a terrestrial globe that could be constructed by the reader.174 Cartography was intimately tied to other cosmographic disciplines such as astronomy, navigation, and especially instrument making during the sixteenth century. Many advances in cartographic precision would emerge from the instrumentation produced in the workshop of Gemma, whom we have already met as the editor of Apian’s Cosmographicus Liber.175 This cross-pollination between cartography and instrument making, with their byproducts visible in cosmography, was also highlighted by Apian and Frisius.176 Like astronomy, revisions to cartographic knowledge would keep pace with the production and use of tools. Printmakers involved in these innovations frequently found it expedient to construct their own presses for their customized publications: such was the case with Waldseemüller and Mercator, in addition to Apian, who established a press in Ingolstadt in 1525.
Waldseemüller and Ringmann’s collaborative publications were among the earliest humanist productions to plot coordinates derived from recent travel accounts of merchants against the world picture established by Ptolemy.177 Vespucci, after all, had also referred back to Ptolemy when accounting for his geographic findings.178 Among the adjustments that Ringmann and Waldseemüller made to the world map was the clearing of space in the Atlantic for a new continent they had the temerity to name after the Florentine merchant who claimed it to be both recently discovered territory and the fourth part of the world.179 Waldseemüller’s map projection can be thought of as a major intervention in the visualization of early modern data, and it reflected a series of visual choices so powerful that it not only rearranged the world picture but also gave birth to one of the largest early modern maps. The size of the printed woodcuts (set together, they measure 4.5 × 8 feet or 1.37 × 2.44 meters), in addition to the effort extended to produce and assemble them, suggests that St. Dié mapmakers were prescient in finding a graphic format to match the size of the epistemic break that using the new name of America would forge. The Waldseemüller map, a document whose touting as the “birth certificate of America” aimed to justify the $10 million price tag that accompanied its sale to the US Library of Congress in 2003, also made a sizable splash at the time of its printing.180
The St. Dié workshop published their new work in productions that privileged pictorial formats and visual “tools” such as globes and maps, but texts still provided the explanatory mortar for the featured visual accompaniments. Ringmann and Waldseemüller’s Cosmographia Introductio, a roughly fifty-page manual, was intended as a primer for this large map. The publication introduced the new territories presented on the map, but the text itself is disappointingly peremptory, disorganized, and visually bereft, especially considering the unambiguous visual impact of the map. It was without clear chapter markings, and the occasional diagrams of the globe with degree and axis markings brought the total number of included images to four. Short shrift is given to spherical astronomy, with a brief sketch of circles encountered on the globe, yet the book is flush with glosses that point to ancient commentators on the world picture, such as Virgil, Ovid, Ptolemy, and Caesar. Three diagrams of spheres try to model celestial astronomy for the reader, and one larger celestial map folds out of the quarto-sized volume. Rudimentary discussions of climate zones are given, followed by lists of placenames. Perhaps the most flamboyant novelty, Vespucci’s discovery of America, is embedded in a discussion of zones and climates, winds, and sections of the world unknown to Ptolemy.
Like the lines dividing the earth into terrestrial circles, “places unknown to Ptolemy,” or extra Ptholomeum, was a time-honored way of demarcating boundaries in early modern geography as a black and white divide, with little gray area. Early sixteenth-century cosmographers were quick to invoke the zonal episteme of extra Ptholomeum for the stark contrast it provided between ancient facts and novelties still struggling for reconciliation. It was a handy scrim on which new data could easily be projected, and a well-functioning model of the order of things. Taking the name Cosmographia from Ptolemy, Apian’s own Cosmographiae Introductio of 1529 still opened summarily with the analogy from Ptolemy that laid out the principles for the notional divisions between geography, which, perhaps most importantly, provided the rhetorical justification for the practice of picturing to convey information.181 Using a woodcut showing the observer’s eye as a vertex for the terrestrial and celestial sphere, Apian borrows for his front matter of this text an image similar to the opening visual gambit of his Cosmographicus Liber in 1524. Despite deference paid to Ptolemy on the first page, Apian invokes Ptolemy later in the text for the purpose of correcting him. If Apian neglects to mention Waldseemüller as a source in the text, he alludes to him in the book’s title and spirit; they shared a kinship in their projects to revise Ptolemy.
Apian’s Cosmographiae Introductio initiated a dialogue with the printed products of the St. Dié workshop. His streamlining of Waldseemüller’s content around graphic design was critical to its production, a characteristic of Apian’s publications post-1524. Apian designed the Cosmographiae Introductio to be a more useful guidebook to the cosmos than was Waldseemüller’s original publication.182 It was divided into clear chapters inspired by Waldseemüller, but then expanded and organized around diagrams that served to explain their principles. Following twelve years on the heels of Waldseemüller’s text, Apian filtered Waldseemüller’s content through the thoroughly visual programs of recent cosmographic publications of his own. He used Ptolemy strategically, placing emphasis on his data – i.e., coordinates – and reinforced his advocacy of visual aids.183 In a text of approximately eighty pages in length, Apian’s choice to include twenty-five images made the visual component substantial. Like his reissue of Sacrobosco’s De Sphaera in octavo format in 1526, Apian’s updating of Waldseemüller was crafted into a handy and portable edition. That it also appeared in Latin perhaps also testified to Apian’s desired crossover appeal to both lay and academic audiences. Printed first in Ingolstadt in 1529, Apian’s Cosmographiae Introductio then went into sixteen later editions in Paris, Cologne, and Venice, including some vernacular printings.184
Apian was forthright about the aspect of Waldseemüller’s Cosmographiae Introductio that he found most important. He privileged the map that expressed the relationship between the astronomical and terrestrial coordinates in a systematic and technological manner. Waldseemüller’s map cast the new data in light of the instrumentation used to obtain it: here, instruments pose as attributes of the protagonists at the map’s top, where Ptolemy holds a quadrant and Vespucci holds dividers, a tool used by mariners and mapmakers. Waldseemüller’s unequivocal emphasis on the visual material contrasts with evidence buried in the text’s ramblings and disorganized quotations from ancient sources.
Apian’s visualization zeroed in on the cartographic advances made in the think-tank of St. Dié in the early 1520s; it was probably exactly these geographic entanglements that partly inspired the production of the book at this chapter’s center, the Cosmographicus Liber. Apian’s terrestrial globe in the graphic description of cosmography on folio 2 was positioned to feature America. But Apian cribbed from Waldseemüller most assiduously in the projection of the terrestrial globe in the Speculum Cosmographicae, a unique instrument in the cosmography to be discussed below.
Several of Apian’s publications prior to the Cosmographicus Liber also took the new world map as their subject, albeit in a slightly altered format. Apian repurposed Waldseemüller’s data in a scaled-down woodblock version of a world map (Figure 2.18), considerably reducing the size of the 1507 original.185 A cordiform projection derived from Waldseemüller, it even borrowed the design of the northern wind head Septentrio, from whose mouth not only gusts but also longitude lines seem to emerge. Designed by Apian for Camertius’s commentary on Solinus, Solini Polyistoria Enarrationes, published in Vienna in 1520, the map appears as a single-sheet foldout tipped into the text near the beginning.186 The map can also be found in some editions of Pomponius Mela’s De Situ Orbis, such as the one that appeared in Basel in 1522. Another publication of Apian’s, the 1521 Isagoge, a short pamphlet of cosmographic propositions, discussed strategies for picturing the earth’s surface, included an explanation of Waldseemüller’s map, and forecasted the author’s plans for a cosmography.187 The announced cosmography is widely believed to have become Apian’s Cosmographicus Liber of 1524. In 1522, Apian provided the text for a pamphlet, Declaratio et Usus Typi Cosmographici (published by Paul Khol in Regensburg), with illustrations by Michael Ostendorfer, including a title page with a south-oriented oval-shaped map that shows a tiny, though assertive, America marked with the initials AM.188 Lastly, twelve globe gores were printed c. 1520 and also are likely from Apian’s press – these certainly appear to be designed to function on the level of a tool, a purpose that the later Speculum Cosmographicae would also serve.189 Apian published the results of Waldseemüller’s findings in these various repackagings, so we should not be surprised that the initial credit for Waldseemüller’s original wall map was in fact usurped by him in the early secondary scholarship. Before the wall map’s rediscovery in the Waldburg-Wolfegg collection in Swabia in 1901, most scholars assumed Apian to have been the first printer to place America’s name on the globe, so avid a promoter was he of Waldseemüller’s findings.190
2.18. Peter Apian, world map in Joannis Camertis … in C Julii Solini Polyistora enarrationes. Additus eiusdem Camertis Index (Vienna: Sigrenius and Alantse, 1520), 28.5 cm × 42 cm.
While it is unclear whether Apian’s cosmography announced in his 1521 Isagoge eventually became the Cosmographicus Liber, it is certainly true that the cosmography was his synthesis of geographic advancements made in St. Dié. Privileging usable information, Apian presented these adjustments to the world map in the unique form of a coordinate dial in the Cosmographicus Liber, an instrument he dubbed the Speculum Cosmographicae (Figure 2.19). This was a geographically oriented astrolabe, in which Waldseemüller’s projection of the earth forms the backdrop of the device. While the astrolabe proper schematized the heavens in order to show what the sky looks like at a given latitude and how celestial bodies move in relation to each other, Apian’s Speculum provided instead information about terrestrial coordinates. On a traditional astrolabe, the bottom-most plate, or mater, shows the stereometric projection of the celestial sphere that maps stars onto the interior of the vault of the heavens. But the mater of Apian’s device carries a projection of the earth seen from the north pole; the dial attempts to set the celestial coordinates into dialogue with their terrestrial analogues.191 Placed at the conclusion of the astronomical part of the Cosmographicus Liber on folio 63, the tool introduces the book’s second half on geography.
2.19. Peter Apian, Speculum Cosmographiae in Cosmographicus Liber (Landshut: Weyssenburger, 1524), fol. 63.
To construct the Speculum’s series of rotating parts, Apian borrowed the design and nomenclature from astrolabes.192 Apian preserves the equator, tropics, and the ecliptic but projects these on top of a terrestrial map, instead of a celestial one. A movable disc carried the ecliptic and zodiac markers. Insofar as it represented a projection of the celestial circle, it mimicked the traditional astrolabe’s star map, or rete, a circle that typically carries the zenith–horizon coordinate system for a particular latitude. Atop this moved the rule that serves as an index or pointer for the front; it is usually marked with a scale of declinations.
Physical astrolabes were outfitted with a number of removable discs that could be set to the local latitude; then, with the aid of a sighting device, or alidade, with which most were equipped on their rear surfaces, sightings could be taken to determine the altitude of sun or stars to find the time in order to appropriately position the discs.193 Modern scholars agree that most astrolabes, until the weighty mariner’s astrolabe that could be stabilized on board a ship became common, were primarily didactic tools for showing the stars and circles in relation to each other. Contemporary readers might have been familiar with publications such as Johann Copp’s Erklärung unnd gründtliche Underweysung alles nutzes, so in dem edlen Instrument, Astrolabium genannt …, which appeared in 1525. This included a ready-to-assemble instrument, along with many images that set store by measurements made by the eye and observers in action.194
The astrolabe permitted investigation of the major terrestrial and celestial lines and attempted to provide knowledge of the celestial system as a whole. But Apian’s instrument rehabilitated cosmography’s intention to combine positional astronomy with geography – by using it to visualize earth-bound observations. Apian’s text preceding the placement of this disc was a summation of five propositions that explained the purpose of this “mirror of cosmography,” among which was to help the user understand the earth in the way one encounters one’s face in the mirror: in other words, to develop visual intimacy with the earth as one knows oneself.195 Again, Apian invokes the epistemic bite of portraiture: just as peering into a mirror would reveal self-knowledge, to observe one’s coordinates was to understand one’s place in the universe.
The dial was intended to help visualize abstract principles – showing readers the processes by which geographic coordinates operate and how to visualize their relationship to the cosmos. Retooling the projections of the traditional astrolabe, the celestial circles have been replaced by a projection of the continents from the north pole. This was a clear sign of Apian’s intention to bring cosmography quite literally down to the study of the earth. After all, this was cosmography’s guiding philosophy. This tool cast the net of celestial lines over a geographic representation of the earth befitting the book’s section on geography. The Speculum volvelle precedes this narrative section and combines astronomical and geographic knowledge, placing it in the text at the threshold between astronomy and geography. The following narrative about continents and a list of coordinates for the world’s cities presents the map as a system that links the celestial and terrestrial realms. The Speculum activates the Ptolemaic system by adding a user interface. The tool helps conceptualize geographic coordinates by having users capture the data themselves in the manner of professional cartographers.
Like the Speculum’s globus, a world map is also a tool. Editions of the cosmography printed after 1544 included a map of the world not present in Apian’s editio princeps (Figure 2.20).196 This was another addition made by Gemma, the instrument designer best known for his contributions to surveying and mapmaking and in whose workshop the future cartographer Gerard Mercator worked.197 Gemma’s position on the faculty of medicine at the university in Louvain hardly alludes to his range of teaching or to the subject areas for which he was responsible, which included mathematics, astronomy, and geography. This map anchored Gemma’s most heavily edited section of the Cosmographicus Liber. The map placed the new discoveries within the discursive context of geopolitical cartography which the image at the top announced: the Holy Roman Emperor Charles V in a Roman cuirass sits with Eolus, the wind, astride a dove.198 The framing figures of this map echoed a trend in the updating of geography by agents already active in Waldseemüller’s map of 1507, the document on which this map is based. Framing revisions to the world picture with portraits of the two empiricists who generated them, Waldseemüller had placed Ptolemy with a quadrant at the top, alongside the navigator Amerigo Vespucci, styled here as Ptolemy’s early modern updater. Both earned their spots in the cartographic firmament on the strength of their reputations as observers, wielding tools of firsthand inquiry and presciently aware of the novelty of their data. By positioning the modern observer Vespucci at the top of his map, Waldseemüller tacitly argued for the agency of instrument users to reshape the world picture. This reference was surely not lost on Apian, who promised that the secrets of geography and spherical astronomy could be unlocked by his own printed tools.
2.20. Peter Apian and Gemma Frisius, world map in La Cosmographie de Pierre Apian,… nouuelleme[n]t traduict de latin en francois (Antwerp: de Bonte, 1544).
The allegorical trappings of empire would dominate the shape of later cosmography, where portraits of sovereigns would edge out the representations of tool-laden empiricists. New discoveries in astronomy and geography would soon be mobilized in the service of geopolitical aims. The empirical basis for cosmography would later surrender to a genre that would feature narrative accounts of the world’s spaces, providing the history of peoples and their conflicts, and a parceling out of what belonged to whom. In this period, we can already detect the slow creep of these empirical projects into the territory of imperial imaginings. Waldseemüller’s edition was dedicated to the Emperor Maximilian, after all, and Apian’s later projects reflect the involvement of Charles V, who commissioned a horoscope from him in the shape of a book with movable dials, the Astronomicum Caesareum.199 Cosmography fell increasingly into the hands of operatives eager to win dominion over geographic territories.200 Later cosmographies (such as those by Sebastian Münster and André Thevet) changed course and “wrote themselves back into medieval, encyclopedic tradition, bestiary, universal history, adding to these recent geographic encroachments.”201 But cosmography as Apian conceived it was still the appropriate genre for both mathematical geography and tools.
Thus, Apian’s Speculum Cosmographicae visualized the main geographic contributions of Waldseemüller’s publications and also raised the profile of empirical study of both the heavens and the world. The Speculum might be the first model to set the jewel of a geographically mapped earth into the setting of the starry vault, an instrument with which stargazers could orient themselves in the broader context of the universe. In short, this model reprises the principles of Apian’s first linear diagram that connected the celestial and terrestrial spheres to the eye (see Figure 2.3). With the Speculum, Apian assembles into one interactive tool all the components of his opening diagram that explains cosmography: this volvelle completes the ambition to graphically depict the world system as a dialogue between astronomical and geographic spheres. At this juncture of the book, users themselves usurp the authority of the prime mover: observers activate the tools with their own hands, producing individually relevant data points.202
Tools and the “Vernacular” Viewer
The Cosmographicus Liber fully endorsed the use of tools as a means for vernacular observers to discover things in their own environment and made explicit that the book’s content was derived largely from firsthand study. Empirical observations not only helped fill in the mortar between the ancient bricks; in some cases, they repaired some of the crumbling patches as well. Karl Röttel has judged the complex visual lessons learned from Apian’s mechanical pictures as a critical intermediary stage for the development, and especially the popularization, of instruments.203 Apian’s translation of mathematized astronomy into visual terms laid the groundwork for a spate of vernacular publications devoted to the use of instruments: sundials, quadrants, astrolabes, and nocturnal dials.204 Apian popularized tools and brought knowledge of them to a much broader swath of the general public. The collection of tools in the Cosmographicus Liber, per the argument of Margaret Gaida, fashioned Apian’s text into a toolkit.205 This amounted to no less than the birth of a new reading public: mathematical autodidacts ready to brave a cosmos that could be unlocked by do-it-yourself tools.
In fact, Apian’s Cosmographicus Liber identified so much as a book about tools that Gemma Frisius commandeered the 1539 edition as a vehicle to publicize his new scientific instrument: the astronomical rings, later called Gemma’s rings. Gemma’s first edits to Apian’s text appeared in Antwerp in 1529; these emboldened him to use Apian’s text as a malleable palimpsest for his own cosmographic musings. Soon after the first edition, in which his corrections appeared in an appendix, Gemma relocated some of Apian’s volvelles into a separate section, likely sensing this as a space that he could later amplify with copy written around his own tools.206 The Antwerp edition printed by Arnold Birkman in 1539 bundled a number of spinoff publications with Apian’s text.207 Birkman’s printing attached Gemma’s appendix on surveying and trigonometry, the Libellus de Locorum describendorum ratione, & de eorum distantijs inueniendis, numquam antehac visus, per Gemmam Frisium, to the cosmography. This text was followed by a thirteen-page discourse on Gemma’s astronomical rings, the Usus Annuli Astronomici, Gemma Frisio Mathematico Auctore, a text that Gemma had printed as an independent short pamphlet in 1534 under the title L’usage de l’anneau astronomique. This practical text featured a number of pictured observers making trigonometric calculations of the altitudes of fortresses and steeples through ringed instruments that Gemma had designed.208 Gemma’s how-to treatise on the rings essentially hijacked Apian’s text in order to publicize his instruments in the appendices. Gemma rewired the cosmography into a manual that would provide the foundation for the use – and, importantly, the sale – of his instruments. This marketing initiative broadened the scope of empirical knowledge that could be processed with the book.
Gemma Frisius became an ardent proponent of the practice of observation. Gemma’s son Cornelius reported in 1561 that his father kept two journals of his own observations. Apparently expecting that perusal of his printed texts would mobilize similar types of data recording, Gemma chastised stargazers for simply following Ptolemy and not using their own observations to update the Alfonsine Tables. The empirical approach that united the interdisciplinary activity of Gemma and Cornelius in the collection of astronomic, weather, and medical data, according to Gianna Pomata, reveals a new method afoot in empirical explorations of the period.209 This type of visual investigation of the world was spearheaded by Apian, but it was endorsed and perfected by Gemma. The move away from doctrine – even when the older sources were still invoked in the contemporary literature – is what united the multiple categories of empirical inquiry that coalesced into a modus operandi for exploring the world. Both Apian and Gemma knew that this user-based interface could best be achieved by images that would chaperone these visual searches in the world picture. These images and tools centered the agency of a literate eye schooled by books.
Images in astronomical texts, mechanical and otherwise, brought lofty principles to earth and sometimes functioned together with words in new pedagogical combinations: images and even verse appear in these books to facilitate understanding for the reader and to encourage personal observation in these pursuits.210 Apian himself capitalized on the content of texts such as Conrad Heinfogel’s vernacular translation of Sacrobosco’s De Sphaera that provided helpful hints about the progression of lunar phases in language that only a layman could love. In the 1516 edition, verses accompany two diagrams that set the sun and moon in relation to each other to explain reflected light from the sun. In the 1533 edition, an unrelated diagram of a lunar eclipse accompanies versions of the original verses:
This was a far cry from their lofty cosmographic precedents; sixteenth-century pointers about astronomy were rendered in doggerel for the practical purpose of serving the reader’s memory. Heinfogel’s use of a jaunty imperative mood was intended to stimulate memory, not unlike lessons learned today by amateur stargazers who need to distinguish between waning and waxing moons with mnemonics such as “when the light is on the right, the moon is getting bright.” Delivery of such wisdom by speaking images was another tactic to engrave those precepts in the mind. The subtitle of this volume – “the path of the heavens together with all of the stars, much easier to learn with the accompanying pictures” – foregrounds its attempt to cultivate a new public of amateur astronomers by way of helpful images.212
A clue to the efficacy of popular astronomy’s visual pedagogy is embedded in one reader’s response to the material. A hand-drawn sheet of astronomic principles that appears in a codex gathering of a book preserved in the Herzog August Bibliothek in Wolfenbüttel cribs from a variety of sources.213 This sheet collates diagrams from Sacrobosco’s Sphera Materialis: Eyn Anfang (the 1533 edition from Cammerlander) and other works of popular cosmography, probably including Apian’s Cosmographicus Liber. A rare example of likely contemporary reception of this material, here we see a reader working out principles of observation derived from the images. One drawing rehearses Sacrobosco’s familiar proof of the ocean’s sphericality demonstrated by the contrasting views of two shipboard observers, one on deck and one at the mast. To clarify the proof, this scribe added another image in which he replaced the actual observers with two eyes, each labeled “Aug[e],” in order to situate the eye at the receiving end of the observation (Figure 2.21).214 With this, he substantiated the agent also at the heart of Apian’s concerns: the eye of the user. Apian frequently animated eyes, ears, hands, and feet in his illustrations. Small, black, thickened stick figures dot his schematic models to provide human receptors for the observations his demonstrations taught. Human actors served as surrogate reference points for the users’ own observations. When the reader of the Wolfenbüttel Sacrobosco saw an unanchored eye in a cosmographic text, it was clear that they did not mistake it for the eye of God; rather, they saw it as their own. With the aid of Apian’s tools, this earth-bound eye peered through the earth into the heavens for the purpose of drawing up a practical data set. This perspective was increasingly conditioned by the visual acuity taught by these manuals and reiterated their promotion of visual knowledge.
Apian himself called on such visual vigilance in his practical publications. He argued vociferously for his own expertise as an observer, a claim that was designed to activate the intended reader to follow in his footsteps. This confidence rested on the premise of the expanse of the heavens over Ingolstadt as a visual horizon he shared with an imagined community of fellow observers whom he hoped to goad into becoming a group of collective empirics: “We see the sky everywhere before our eyes because it spins day and night around the earth, and we would like to easily observe and describe it.”215 In the prologue of his Practica auff das 1532. Jar, Apian distinguishes the empirical knowability of the heavens from that of the earth. Because the earth stretches beyond the visual field of the observer, it presents a greater challenge to description because it cannot be encompassed without costly travel. On the strength of his visual acuity, Apian intones, the reader should summon the services of an astronomer who has been observing and recording the effects of the stars on weather and storms (the topic of this almanac), because he has trained his eye to track these conditions.
Peter Apian led the era of publishing cosmographic texts framed as methods to train the visual aptitude of amateur observers. Packaged for new readerships, this foray into new territory and its fallout can be tracked in new vernacular manuals that capitalized on the gathering of empirical knowledge. The age of Apian’s publications was firmly dedicated to serving up usable manuals to new devotees of astronomy. Apian situates his reader locally (important to cosmographical accuracy) and provides demonstrations of things that can be observed on earth. Never asked to take phenomena on faith alone, Apian’s readers were provided with a theoretical armature to accompany their search for events in a visually constituted field. We need only remember Apian’s pictorial demonstration of how the shape of the earth can be visually verified during observations of lunar eclipses: we see the roundness of the earth projected onto the eclipsed moon. Apian reminds his readers that if the earth took the shape of a square or triangular or hexagon, they would instead see these shapes reflected on the lunar surface. As a direct and easy appeal to the eye, the point is shored up by a rhetorical directive to the viewer: compare and contrast. What the naked eye sees can unpack larger principles. How-to tools that helped activate and contextualize both astronomical and geographical observations centered them no longer around a theoretical “eye,” but around an actual earth-bound “Aug[e].”
