The atomic theory of Dalton implied that there were more than 30 different kinds of matter, the chemical elements. William Prout (1815) was the first of a long line of distinguished speculators who sought to show, by argument and experiment, that this diversity overlay a more fundamental unity. Contrary to a common opinion, this was not an eccentric and unpopular movement, but involved many of the great names of nineteenth-century chemistry; and some of their speculations have proved to be very near the mark. It may be that this strong current of well-informed speculation enabled the discoveries of cathode rays and of radioactivity (which provided the first real evidence of the complexity of the atom) to be integrated into the body of science with such remarkable rapidity.

It has become generally accepted that the earliest geoheliocentric representation of the planets' motions in which the majority of the planets orbited about the Sun appeared in 1588. For in this year the Danish astronomer Tycho Brahe announced his discovery of a new system of the world, in which Sun and Moon moved about the Earth, and the five planets Mercury, Venus, Mars, Jupiter and Saturn performed their motions about the Sun. Yet the accompanying figure, which depicts a planetary arrangement in general identical with that of Tycho, occurs in a manuscript prepared at least a year before Tycho's publication of his system. Moreover, the author of the manuscript derived this representation of the planets' motions not from Tycho, but rather from Copernicus. The aim of this paper is to show that as a result of the work of Copernicus, a number of sixteenth-century mathematicians produced treatments of the planetary motions similar to the system proposed by Tycho in 1588.

Johann Gregor Mendel read his paper, “Versuche über Pflanzenhybriden”, to the Naturforschender Verein in Brno, in two parts, the first at the Society's meeting on 8 February 1865, and the second at the next meeting a month later. It was subsequently published in the Society's proceedings for the year 1865 which appeared in print in 1866.

As early as 1670 Isaac Barrow and Isaac Newton, at Cambridge, were aware of the production of astigmatism by oblique pencils of rays on a spherical lens. Thomas Young (1800) and G. B. Airy (1825) independently discovered ocular astigmatism. By viewing the image of objects reflected on the anterior surface of the cornea, the cornea may be examined for any defects of its surface (including astigmatism). The corneal “reflex” had been examined as early as 1619 by Christoph Scheiner, and as a “clinical” test, by using a candle flame, by David Brewster (1808). An instrument (the keratoscope) for examining the anterior surface of the cornea for the detection of abnormality was first invented by Henry Goode (1847) of Cambridge University. Antonio Plácido, formerly credited with the invention, independently invented a keratoscope in 1880. Correspondence of Plácido and Emile Javal (Paris) reveals that Placido invented the photo-keratoscope, formerly attributed to Allvar Gullstrand (1896) in Sweden. Javal is credited with the first description of the application of a photo-keratoscope (independently invented by him) in a specific case of ocular abnormality.

For fifteen years, from 1662 until his death in 1677, Henry Oldenburg served the Royal Society as second Secretary and was charged with almost the entire burden of its correspondence, domestic and foreign. During this time he acted as a centre for the communication of scientific news, searching out new sources of information, encouraging men everywhere to make their work public, acting as an intermediary between scientists and, through the Philosophical Transactions, providing a medium for the publication of short scientific papers. Oldenburg's contribution to scientific communication was unique in the seventeenth century, not least because he represented the Royal Society (of which he was an original Fellow) and served all its members impartially. It is not too much to say that he invented the professions of scientific administrator and scientific journalist.