By the discovery of the different refrangibility of light, Sir Isaac Newton laid open the true cause of the principal imperfection of refracting telescopes; and having inferred from the experiments which he made, that the refraction of the different rays composing the prismatic spectrum, was always in a given ratio to the refraction of the mean refrangible ray, this great philosopher was led to conclude, that the imperfection which he had discovered in dioptrical instruments was without remedy.

Since reading the paper upon the theory of the earth, I have been employed in examining many parts of this country, in order to enquire into the natural history of granite. In this undertaking, I have succeeded beyond my most flattering expectations; and I am now to communicate to this Society the result of my observations.

In the paper just referred to, it was maintained, from many different arguments, that all the solid strata of the earth had been consolidated by means of subterraneous heat, softening the hard materials of those bodies; and that in many places, those consolidated strata had been broken and invaded by huge masses of fluid matter similar to lava, but, for the most part, perfectly distinguishable from it. Granite also was considered there as a body which had been certainly consolidated by heat; and which had, at least in some parts, been in the state of perfect fusion, and certain specimens were produced, from which I drew an argument in support of this conclusion.

No quality is more inconsistent with the character of a stone than flexibility. A flexible stone, therefore, presents an idea which naturally strikes us with surprise. For though among mineral bodies, we find flexible substances of the stony kind, such as mica, mountain leather, and amianthus, these minerals owe their flexibility, either to their thinness, or to the fibrous structure of their parts. Therefore, when a stone of any considerable thickness is said to have flexibility, we are led to think that here is something very extraordinary; and we wish to know upon what depends that quality, nowise proper to a stone.

Sir Joseph Banks, to whose indefatigable ardour for the advancement of natural history, the philosophical world is so much indebted, made a voyage to Iceland in the year 1772, to enquire into the productions of that remote part of the world, and particularly into those of its famous volcano. When he returned, he brought from thence, among many other natural productions, some petrified vegetables, and incrustations, formed by the waters of the boiling springs; and he was so good as to present a part of them to his friends here, who were surprised to find them composed of siliceous earth. As this was the first example observed, of water containing this earth in such quantity as to form siliceous petrifactions, it raised a strong desire to have an opportunity of examining the water, and of learning by what means this siliceous matter was dissolved in it; and this opportunity was at last given us by John Thomas Stanley, Esq; who, excited by motives similar to those of Sir Joseph Banks, equipped likewise a vessel, and made a voyage to Iceland, during the summer 1789.

Dear Sir,

I have been prevented hitherto, by various occupations, from acquitting myself of a promise you received from me, (I am ashamed to think how long a time since), that I would send you an account of the hot springs in Iceland, from whence the water was brought which you have lately analysed. I have trusted you would excuse a delay not altogether voluntary. It will be now my endeavour to gratify your curiosity as far as I am able; and to acquaint you with every particular, as well concerning the springs as the country near them, which I think you may find in the least interesting.

Dear Sir,

Part of my promise has been accomplished in a former letter, in which I gave you the fullest account I could of the springs of boiling water that rise in the valley of Rykum. It now remains for me to send you a description of those we visited in the neighbourhood of Haukadal.

These last are the most remarkable in the island, and the eruptions of water from some of them so astonishing, that I doubt whether any adequate idea of their effect can be given by description. Abler pens than mine might fail probably in attempting to do justice to such wonderful phenomena. The objects, however, are so highly interesting in themselves, that even the simplest narrative that can be given of them will be read with more than ordinary attention.

The restoration of the ancient books of geometry would have been impossible, without the coincidence of two circumstances, of which, though the one is purely accidental, the other is essentially connected with the nature of the mathematical sciences. The first of these circumstances is the preservation of a short abstract of those books, drawn up by Pappus Alexandrinus, together with a series of such lemmata, as he judged useful to facilitate the study of them. The second is, the necessary connection that takes place among the objects of every mathematical work, which, by excluding whatever is arbitrary, makes it possible to determine the whole course of an investigation, when only a few points in it are known. From the union of these circumstances, mathematics has enjoyed an advantage of which no other branch of knowledge can partake; and while the critic or the historian has only been able to lament the fate of those books of Livy and Tacitus which are lost, the geometer has had the high satisfaction to behold the works of Euclid and Apollonius reviving under his hands.

The Quassia Polygama has long been known in Jamaica, and in fome other islands in the West Indies, not only as an exexcellent timber, but as an useful medicine in putrid fevers and, fluxes. With us, it is called Bitter-wood, and in the Windward Islands, the Bitter Ash. The bark has for some time been prescribed by practitioners here, and exported to England in considerable quantities, for the purposes of the brewers of ale and porter. On these accounts, a fuller description of this plant than has hitherto appeared, will be acceptable to the botanist and the public at large.

This monster, of which the mother was delivered by Mr Thomas Anderson, surgeon in Leith, after the birth of a complete child at the full time, had its proper membranes and a placenta, with a short umbilical cord.

The following parts were wanting in it; to wit, the bones of the head; the brain, with the organs of sight, hearing, smell and taste; the neck; about one half of the ribs; the larynx, trachea and lungs; the heart; the pharynx, œsophagus and stomach, with all the small intestines, except the end of the ilium; the anus; the liver, spleen, pancreas and omenta; the renal glands; terminations of the ureters; the middle part of the urethra; the right testicle; both arms; both patellæ; with several of the bones of the feet and toes.

On the 3d of November last, Sir James Hall and Dr Rutherford asked me to repeat with them some experiments on what has been called Animal Electricity, which were first performed by Dr Galvani, Professor of Anatomy at Bologna, and of which an account had been communicated by Mr Seguin of Paris to Dr Black, in a letter dated Paris, 3d August.

Dear Sir,

The earthquakes which have lately taken place at Comrie and its neighbourhood, are certainly very deserving of attention. I shall therefore cheerfully comply with your request, and give you as particular a description as I can of such of them as have been most remarkable. To give a particular account of all the noises or concussions which, during the last half-year, have been heard or felt at Comrie, and within a short distance to the north, east and west of that village, is beyond my power, and would indeed be of little use.

The following improvement on the construction of the thermometer, by which it is fitted to mark the lowest or the highest point to which the fluid has attained in the absence of the observer, is due to John Rutherford, M. D. of Middle Balilish. This gentleman communicated it to me some time ago, and accompanied the description with one of his thermometers. The contrivance is so very simple and ingenious, that it well deserves to be made public. I therefore, by permission of the author, beg leave to lay an account of it before the Royal Society.

As it appeared to me, when I first began, in 1759, to deliver in this University a public course of lectures on Anatomy and Surgery, that the structure of the oblique muscles had not been sufficiently examined, nor even the number of them attended to by authors, and that some of their chief purposes or effects had been ent rely overlooked by them, I endeavoured then, and in every course of lectures since that time, to direct very particularly the attention of students to those subjects.

The mosses of Kincardine and Flanders are situated in that extensive plain or carse which begins at Borrowstounness, on the south side of the Frith of Forth, and a little above Eastern Kincardine, on the north side. It stretches along both sides, first of the Frith, and afterwards of the river Forth, as far as Cardross, about twenty-two miles west of the point where it begins. The breadth of this plain, or carse, at Falkirk, where it is widest,is about seven miles, including what is occupied by the Frith.

Ala suite du voyage d'Italie, j'attendois à Venise une occasion favorable pour entreprendre celui de la Grèce. Le Chevalier Zuliani, nommé Ambassadeur de la République auprès de la Porte Ottomane, alloit incessamment partir pour sa destination; je lui demandai une place sur son vaisseau, et je fus assez heureux pour l'obtenir. Cet Ambassadeur, qui réunit à toutes les qualités d'un habile negociateur, le gout le plus décidé pour les arts et pour les sciences, avoit aussi reçu dans son vaisseau le célèbre Docteur Spallanzani, l'un des plus ingénieux naturalistes de ce siècle, que l'Empereur Joseph II. envoyoit dans le Levant, pour enrichir la science de la nature de découvertes nouvelles.

Words that are precisely equivalent are rarely, if at all, to be met with in any language. Those properly called synonymous, exhibit one leading circumstance in which they all agree, and one or more accessory circumstances in which they differ. When the point of their general coincidence, and the grounds of their particular diversities, are clearly ascertained, it is then in the power of the writer to use them with propriety. By the assistance of the grammarian, he knows which to adopt and which to reject, and can reconcile embellishment with accuracy and precision.

In some other dissertations, I have endeavoured to investigate the original country of the Iones, Dores, Æoles and Achæi or Achivi; and have, I hope, shewed, that none of these tribes were aborigines of Greece. In this paper, I shall trace the origin of the Hellenes, a people who, in process of time, be came so considerable, that all the other septs and petty clan ships of that nation were proud of being called by that venerable name.