The interest awakened by Gay-Lussac's great discovery of the simplicity in the relation of the volumes of gases has greatly increased in recent times, when chemists have discovered that, in a large number of instances at least, the formula of a body, as deduced physically from its vapour density, exactly coincides with that deducible from chemical considerations of its reactions, and from the nature of the products arising in consequence of them.

The processes at present used for determining the vapour densities of bodies, are those of Gay-Lussac and Dumas.

In 1845, a paper by me on the balance magnetometer was read to the Royal Society of Edinburgh (see Trans. vol. xvi. p. 67), which contained an examination of some of the difficulties to be considered and overcome in relation to that instrument. No similar examination has yet appeared, as far as I am aware, of the bifilar magnetometer. When it is considered that the value of the results obtained from this instrument in so many observatories is dependent on an exact knowledge and elimination or correction of its errors; and, as will appear hereafter, that the temperature coefficients employed in the discussion of the Colonial observations are in some cases so erroneous that the unconnected observations would have been nearer the truth than after correction, the following communication may not appear unnecessary.

These notes have been made at different intervals of time, and in different places,—some, and the majority of them, in Malta, in 1832–33,—some at Constantinople in 1839–40, and a few at a still earlier period, viz. in 1816, when on a voyage to Ceylon.

Imperfect and brief as many of them are, I am induced to submit them to the Society, thinking they may be of some use as conveying the results of unbiassed observation, and that, as such, they may prove a small contribution, to a difficult branch of icthyology,—difficult, not indeed so much from the nature of the subject as from the comparatively few opportunities enjoyed by naturalists of obtaining specimens.

Amongst the natives of Ceylon, the occurrence of the Albino, the offspring of dark-skinned parents, is not very uncommon. In looking over my note-books, kept whilst I was in that island, between the years 1816 and 1820, I find mention made of five several examples. Now that the subject of species and varieties is attracting so much attention, perhaps the particulars I then collected of these abnormal instances of the human race may not be altogether without interest, even if given a little in detail.

The only observations made with Dr Lloyd's bifilar magnetometer, published with corrections applied to the individual observations, are those made in the Makerstoun Observatory, forming part of the Transactions of the Royal Society of Edinburgh. The results obtained from these observations (especially from those for 1844 and 1845), were first compared by me in 1856, with observations (also corrected by myself) made in the Trevandrum Observatory during the same years. The singular resemblance of the variations of daily mean intensity thus discovered at two places so distant, and so differently situated on the earth's surface, induced me to undertake the considerable labour of determining the temperature coefficients, and of correcting and discussing all the published (and some unpublished) observations made in the colonial observatories. This labour was too great to have been undertaken by me alone, in consistence with my other duties, and it is due to the liberality of His Highness the Rajah of Travancore, that I could employ in part for this work the computers attached to his Observatory.

The bearing which the subject of the following communication has upon the much-vexed question of the unity of the human species, and the inferences which may be drawn from it in relation thereto, invest it with an importance which would not otherwise belong to it.

The position which the question I allude to at present occupies is this. On the one hand, the advocates of the view that all men are not of the same species, but that they compose a genus consisting of many species, maintain that the parasites which infest the different races of man are distinct; and because we usually find that distinct species of parasites are allotted respectively to the different species of the lower animals, they infer that the same rule must hold with man, and that therefore each different race possessing a distinct parasite must be a distinct species.

The excursion described in the following pages was planned by Dr Macpherson, Inspector-General of Hospitals, and myself, with a view to explore the Southern Range of the Anamalai (i.e. Elephant Hills), in the district of Coimbatore, which are sparingly laid down in the Great Trigonometrical Survey Map, while the peculiarities of their Fauna and Flora had not been recorded.

The project was approved by the Right Honourable Lord Harris, then Governor of the Madras Presidency, and the services of Major D. Hamilton were sanctioned by His Excellency Sir Patrick Grant, Commander-in-chief, to accompany us as artist, to delineate the characteristic features of the country.

Sir Thomas Brisbane was born at Brisbane House, Largs, on the 23d July 1773. He was descended from the Brisbanes of Bishopton, one of whom, according to Hailes, “held the office of Chancellor of the kingdom of Scotland in 1332.” They possessed a large tract of country, extending from Erskine Ferry to Largs; and had this estate been still in their possession (consisting, as it did then, of Bishopton, Greenock, Ardgowan, Skelmorlie, Largs, and Brisbane), its revenues would have been princely; but Sir Thomas only inherited the smaller portion of the possessions of his ancestors, Largs and Brisbane.

In a paper on the Polarisation of Light by Refraction, published in the “Philosophical Transactions” for 1814, I have shown that when a pencil of light is incident on a number of uncrystallised plates, inclined at the same or different angles to the incident ray, all their surfaces being perpendicular to the plane of the first incidence, the transmitted pencil will be wholly polarised, when the sum of the tangents of the angle of incidence upon each plate is equal to a constant quantity, depending upon the refractive power of the plates and the intensity of the incident pencil.

Some years ago I commenced an examination of the behaviour of the so-called olefines towards certain compound halogens. I was induced to this by the conviction that the bodies resulting from the union of a group of unequally chemico-negative elements with an olefine, would place an instrument of great power into the hands of systematic chemists, especially of synthesists. My expectations have been more than realized. The few olefines which I have examined in their relation to compound chemico-negative groups have given rise to a series of new bodies remarkable alike for their great number and for the elegance and importance of the reactions attending their formation and recompositions.

In the Geology of Scotland, no feature comes at once more prominently before the observer than the number and variety of the trap-rocks. From the Sheant Isles to the Cheviot Hills the map is dotted over with trappean patches, which occur sometimes as long, narrow dykes, and often as irregular sheets, that extend almost over entire counties. The appearance of the rocks on the face of the country is scarcely less marked than on the map, and to their ever-changing varieties, we owe not a little of the characteristic scenery of Scotland. Throughout the wilds of the Inner Hebrides it is the trap-rocks which form many of the precipitous cliff-lines, and the craggy irregular hills. The soft pastoral valleys of the Ochils and the Pentlands lie among trappean rocks, while the hill-ranges, which break up the great central valley of Scotland, more especially the abrupt solitary crags that form such prominent landmarks, owe their existence to the permanence of the trap-rocks of which they consist. In short, there is no group of rocks more constantly found throughout the length and breadth of the island, and none, therefore, which so frequently obtrudes on the geologist or more imperatively demands his attention.

If it be true that “there is a history in all men's lives, figuring the nature of the times deceased,” how much more worthy of record the lives of those who have left an impress upon their age, who have corrected popular errors, have made clear much that was obscure, and, from the force and fulness of truth in them, have become the great teachers of their time. The histories of such lives figure more than the “times deceased,”—they teach us how to occupy our time; and though these earnest men are dead, their works are yet living epistles, ever speaking to those “who have ears to hear.”

The solid compounds of carbon and hydrogen form a class of substances to which chemists have scarcely, as yet, paid that attention which their importance and interest appear to merit. With the exception of naphthaline, very little is known regarding them, and it is remarkable that the numerous and varied products of decomposition obtained from that singular substance should not have induced a more minute examination of the kindred compounds, whose existence has been indicated by different chemists. The interest attaching to these compounds is all the greater because, according to their discoverers, several of them are isomeric, or at least polymeric, with naphthaline; and a more careful examination of them might be expected to throw some light on their intimate constitution, and relations to that body.