The following additional observations on the comparative structure of the eye-ball, are intended chiefly to illustrate the philosophical anatomy and physiology of the capsules forming the Canal of Petit, and of the Marsupium Nigrum; yet as I have here taken notice of several other points in the comparative anatomy of the eye, the memoir may be considered as supplementary to those formerly read to this learned Society, and which it did me the honour to insert in its Transactions. I have stated in the first of those essays, that I had been led to inquire into the structure of the Eye, partly as connected with researches into the comparative anatomy of all the organs of sense, but more particularly with a view to elucidate the nature and distribution of the nervous system. I did not presume to think that any remarkable peculiarities in the structure of this most interesting organ, had escaped preceding anatomists; but though I found this to be true, in so far as regards the structure of the eye in most of the mammalia, it yet appeared that the same organ in other vertebral animals had by no means been investigated, or at least describedj with the same care.

As the following anomalous case relating to the vision of colours, appears to possess some remarkable peculiarities, I have considered it of sufficient importance to be submitted to the Royal Society of Edinburgh.

J. B., aged 60 years, served in early life an apprenticeship to a farmer; but, disliking agricultural pursuits, became a tailor, and afterwards entered into the Navy, and served in several general actions. After quitting the sea-service, he resumed his trade, and in the employment of which he now continues. From his childhood, it appears, he was unable to point out colours by their proper names; or, excepting in a few cases, to distinguish one colour from another. From the nature of his avocation, this circumstance must have often been to him the source of much inconvenience; and during his whole life, he has found the utmost embarrassment from it.

Since the perfecting of a Natural Arrangement has become the grand object of scientific pursuit, it has been found necessary to enter more minutely than was required by an artificial system, into modifications of structure and function. Botanists have no longer rested satisfied with observing plants in their fully developed forms, but have also had recourse to several other periods in the existence of vegetable life, the observance of which gives much insight into the organisation of the individual. Of these there is none more important than germination, which is often the only means afforded for ascertaining the structure of the seed. This is the case with all the cryptogamic tribes, the seeds of which are generally so minute, that many of them must be brought together before they be distinctly visible.

Few cabinets of minerals contain so many of the rare substances, which were discovered in Greenland, by Sir Charles Giesècke', and perhaps none in equally interesting varieties, as that of Mr Allan. The most prominent of them hare been examined both in a mineralogical and chemical point of view, and some described as particular species. Mineralogy is already indebted for Allanite, Sodalite, Eudialyte, and Gieseckite, to the zeal of die indefatigable explorer of Greenland, and the subsequent labours of Dr Thomson and Professor Stromeyer; and it is probable that the number of new species from this source will yet be increased upon farther examination.

Alexander Wilson, M. D., late Professor of Practical Astronomy in Glasgow College, was a younger son of Patrick Wilson, town-clerk of St Andrew's, and was born there in 1714. He was very young when his father died, and was afterwards brought up by the care of his mother, Clara Fairfoul, a person much respected for her prudence, virtue, and piety.

Having received the usual education at the different schools, he entered to the College of St Andrew's, where he made great proficiency in literature and the sciences, and, after completing a regular course of studies, was admitted to the degree of Master of Arts in his 19th year.

A. Justly celebrated Naturalist was of opinion, “that every “distribution of mineral bodies, which is instituted before the “determination of the species, must be mere confusion; while, “after having established it, according to fixed principles, no “kind of distribution can be absolutely faulty.” The distribution itself varies, along with the different principles of classification, introduced for the purpose of obtaining a systematic arrangement, conformable to the views of Natural History, of Chemistry, or of other sciences; but the Species remains that unique and unalterable point to which every system, and in fact every inquiry, must be referred, if we wish to avail ourselves of the prerogatives of the human mind, and preserve our information in a scientific form.

The public attention, animated by scientific controversy, has of late years been much directed to Geological subjects; and the certainty of many important facts, has in consequence been ascertained beyond dispute, which were formerly unknown, or at least involved in such obscurity, that no person could have ventured to assert them, without being charged with extravagance. But though, no doubt, many branches of this science still remain to be investigated, such inquiries may now be said to have acquired a considerable degree of consistency and interest, from the substantial basis upon which they have been found to rest.

The two Comets which are the subject of this communication were discovered at Paramatta; the first by Mr Rumker, and the second by our countryman Mr Dunlop.

The elements of both have been calculated from the observations of Mr Rumker and Mr Dunlop, by Mr George Innes, Aberdeen, and Mr James Gordon, A. M.

It is universally admitted, that, in the present advanced stage of Meteorological Science, nothing would be more desirable than complete and accurate registers of the indications of Meteorological Instruments,—more especially of the Thermometer, Barometer, and Hygrometer, such registers being cotemporaneously kept at numerous places, and at various elevations on the earth's surface. Many are the obstacles, however, which have been found opposed to such an acquisition.

In the course of some inquiries into the affinity and structure of the Greek and Latin languages, I was led to analyse the superlative degree of both, and to trace, as I thought, some connection between it and the word Sublimis. While engaged in the investigation, I was naturally led to examine the common theories respecting the etymology of this remarkable word, and, in particular, the origin assigned to it by the late Dr Parr, and to weigh, with more attention than I had previously done, the arguments and proofs he had advanced in support of his opinions. All that I knew of them, till lately, was by verbal report, as I had not seen the abridged statement of them in an Appendix to the Notes of the 2d edition of Mr Stewart's Essays.

In the year 1820, I had occasion to suggest to the Royal Society the propriety of establishing Registers of the Thermometer in various parts of Scotland.

In a country embracing so many varieties of soil, climate and elevation, and extending over nearly six degrees of latitude, it was an object worthy of a public body to determine the Law of the Distribution of Temperature, even if such a subject had not possessed a separate interest in relation to the Horticulture and Agriculture of the Country. The Society did not hesitate in adopting this suggestion, and many intelligent individuals were found, who undertook to observe the thermometer twice a-day, and to measure occasionally the temperature of Springs and Wells, During the first year, viz. 1821, nearly sixty Meteorological Journals were regularly kept in different parts of Scotland. The number diminished considerably in subsequent years; but, notwithstanding this diminution, there is now in our possession a rich series of observations during five complete years, the results of which are nearly ready to be submitted to the Society.

A history of the revival of literature in Europe, after its extinction in the middle ages, has been long a desideratum in the annals of human knowledge; and from the wide, and almost untravelled field, which such a history would embrace, and the recondite sources of information which must be consulted, it will perhaps be long before any individual is found with sufficient learning to estimate its difficulties, and yet hardy enough to attempt to overcome them.

In the Paper which I had the honour of submitting to the Society, on the Two New Fluids in mineral bodies, I have given the index of refraction for the most expansible of the two, as it exists in the cavities of Amethyst; but as I had not then ascertained the refractive power of the second fluid, and as the principal phenomena of the two fluids, especially those which related to their properties when taken out of the cavities, were observed in specimens of Topaz, it became desirable to have an approximate measure of the refractive power of both of them, as they exist in that mineral. As the fluid in Amethyst had never been examined in the open air, its identity with that in Topaz was inferred solely from the equality of their expansion by heat, so that the determination of the refractive power of the latter was necessary to establish either a difference between these two substances, or their perfect identity.

The Natural History of the Pholades, so far as regards their mode of burrowing in wood and stone, seems yet to be but imperfectly understood, though the Pholas was known to the ancients, and Pliny notices its phosphorescent quality. Rondeletius, Johnston, and Rumphius have figured several species; Lister, among others, gives representations of three British species, the Pholas dactylus, Candida, and crispata; and Sir Robert Sibbald, in his Prodromus, has three rude figures of the dactylus or crispata, as Scottish shells. None of these authors, however, attempted to explain how the Pholades excavated their habitations in the rock, or perforated the submerged wood in which they seek protection. Bonanni, so far as I know, was the first who turned his attention particularly to this inquiry.

On a former occasion, I had the honour of describing and exhibiting to this Society a new Registering Thermometer, by means of which the atmospheric temperature may be ascertained at any given instant during absence. In the construction of the instrument then described, a sliding index within the tube is indispensable; and, whenever such an index is employed, the diameter of the tube, and consequently that of its bulb, must be such as to render the instrument defective, when great accuracy and attention to minute fractions is requisite, such as in barometrical measurements, and various delicate experiments. Besides, though an instrument made with such an index may be so constructed as to perform with great accuracy, still, inasmuch as it is a complication, it is defective, and is more or less liable to error, as its construction may have been moire or less perfect.

The celebrated Bouguer was the first who discovered the important fact, that the eye can detect a very small difference between two similar illuminated surfaces, when viewed at the same moment,—the only principle which has yet been applied with any degree of success, in determining the relative illuminating powers of artificial flames. The following is perhaps the most commodious application of this principle, to determine the relative illuminating powers of different artificial lights, particularly of coal and oil gas. The instrument, or photometer, which I employ for this purpose, is extremely simple. It consists of a rectangular box, about an inch and a half, or two inches square, open at both ends, and blackened within for the purpose of absorbing the stray-light.