Dr Fleming began by stating, that a paper of his, “On the Neptunian formation of Siliceous Stalactites,” was read before the Society, March 7, 1825, and published in “Brewster's Journal of Science,” for April of the same year, p. 307. To this paper Dr Hibbert has referred, in his description of the “Limestone of Burdiehouse,” Edin. Phil. Trans., vol. xiii., p. 280, but has misrepresented, in an unaccountable manner, the facts which had been stated. Dr Fleming, expressly said, in describing a limestone containing the remains of dicotyledonous plants, and consisting of flinty and calcareous layers, that it “dips under the great bed of limestone belonging to the coal formation which extends north towards Linlithgow,” which “encloses the remains of those marine animals which are common in the limestones of the coal formation.”

After some prefatory remarks on the general character of the greywacké formations in the south of Scotland, on their entire destitution of organic remains, or even decided impressions, and on the general prevalence of marks, produced apparently by shallow water, a singular series of schistose strata is described, of little more than two feet in thickness altogether, presenting everywhere peculiar features. First, there are two opposed surfaces, the one sprinkled over with thin, short, raised streaks, and the other with small cylindrical grains, all lying perfectly parallel to each other, and consisting of a hard substance, differing from the material and colour of the greywacké rocks. Next, there are a few seams of fine schist, and then a surface, covered with minute, sharply-defined indentations, having every one a lip turned up on one side, and sometimes clinging to the lip, a small speck of the same hard brown substance, which appears on the two surfaces first mentioned.

Many remarkable diversities of temperature are observed in this island, which have not yet been satisfactorily accounted for, either by difference of latitude or of elevation, by shelter or exposure, or by the influence of currents in the ocean. It is attempted to shew that other causes usually assigned have no validity,—that the proximity of high, and consequently cold mountains, has no effect in cooling the low ground near them, even when their summits are covered with perpetual snow, and that a difference in the clearness of the sky, or in the radiating power of the surface of the ground, produces no effect on the average temperature.

On the Shell referred to by Ure in his “History of Rutherglen and Kilbride,” as “a species of Patella.”—Dr Fleming called the attention of the Society to the extraordinary merits of Mr Ure, who died in 1798, leaving a memorial, in the work above referred to, and which was published at Glasgow in 1793, of an acquaintance with organic remains unequalled on the part of any contemporary author of the United Kingdom. This work, however, is very seldom referred to by modern palæontologists, although eminently useful in illustrating the progress of discovery. It was likewise stated, that an additional degree of interest must be felt by the members of the Society, in consequence of a collection of organic remains, chiefly marine, and from the carboniferous limestone, which belonged to Mr Ure, having been presented by Mr Stark, and which now occupies a place in the cases up stairs.

This instrument, which has been invented in America, consists of an electro-magnetic machine, which, being placed in connection with an ordinary astronomical clock, does not interfere with the regularity of its going, while it marks the instant of each vibration of the pendulum on a revolving cylinder, whose circumference moves at the rate of one inch per second. Two wires being then taken to an observer at any distance, if he, when he observes a star crossing the meridianwire of his telescope, makes contact with the wires, that moment is immediately marked on the same moving cylinder where the even seconds are registered. The fraction of a second may be then obtained with as much accuracy as the space of an inch may be subdivided by ordinary mechanical means: say to the hundredth of a second. This method is further available in many cases where the present mode of noting transits is not, and admits of a great multiplication of observations during the short space of time that the star occupies in crossing the field of view.

This paper commenced with an outline of the nature and history of the problem of rolling curves, and it was shewn that the subject had been discussed previously, by several geometers, amongst whom were De la Hire and Nicolè in the Mémoires de l'Academie, Euler, Professor Willis, in his Principles of Mechanism, and the Rev. H. Holditch in the Cambridge Philosophical Transactions.

None of these authors, however, except the two last, had made any application of their methods; and the principal object of the present communication was to find how far the general equations could be simplified in particular cases, and to apply the results to practice.

Messrs Smith stated that they had extracted from the dandelion, a large amount of a crystalline sweet substance, having all the physical characters of mannite. It was analysed by Dr Stenhouse, and found to contain carbon, hydrogen, and oxygen, in the proportions which characterise the accepted formula for mannite; viz., C6 H7 O6, so that it certainly was the substance it was supposed to be.

The author, after referring to the principle on which the intense batteries of Daniel and Grove are constructed, and to the disadvantages connected with the use of the porous cells in those arrangements, stated that he had some time ago instituted a series of experiments, with a view to the construction of a voltaic circle of high electro-motive force, capable of being excited by a single solution, similarly to the battery of Mr Smee. Having employed a great variety of solutions, he was led to consider mixtures of chromic or chlorous acid with dilute sulphuric acid, best adapted to the purpose he had proposed.

The writer of this paper commenced by stating his purpose of viewing Dr Chalmers as a public character only, and to avoid all questions which belonged to the peculiar relations in which he stood to his own religious communion; and after a brief outline of the various circumstances of his life, and the dates belonging to each, the paper proposed to consider Dr Chalmers,—

I. As an Author.

II. As a Political Economist.

III. As a Speaker.

The author began by defining probability as being that state of mind in which we are inclined to believe a proposition, without being absolutely convinced that it is true. Objectively, every proposition is either true or false; subjectively, it may be certainly true, probable, or impossible.

The measure of probability he shewed to be the same as the measure of the cause producing it; that is, the ratio of the reasons inclining us to believe a proposition, to the whole number of reasons bearing upon it, whether for or against; all of which reasons are founded, either upon necessary inference from experience, or from testimony.

The author's object in undertaking these experiments, was to discover if the achromatism of the eye could be accounted for by the differences in the dispersive ratios of the fluids forming that organ.

The indices for several of the fixed lines were determined in the aqueous humour; with the crystalline no satisfactory result could be obtained.

The object of this communication was to ascertain the relation between the apparent brightness of a light, and the time during which it acts on the eye. In order to examine the intensity of luminous impressions of short duration, the author made use of discs, having sectors of known angles cut out of their circumferences, which were made to revolve at known velocities between the eye and a luminous object. In this manner, the object is seen at each revolution of the disc for a short interval of time, of which the duration is easily ascertained. An instrument termed a selaometer (from σελας, brightness), to indicate its use as a measure of the intensity of luminous impressions, was devised for the purpose of comparing the brightness of the flashes caused by the revolution of the disc, with a light of known intensity.

In this paper an account was given of grooved, striated, and abraded rocks in various parts of Scotland, from Glen Spean on the north, to the Pentland and Lammermoor Hills on the south. After indicating the direction in which the groovings pointed, it was shewn,—that the appearance of these grooved and striated rocks is irreconcilable with the hypothesis which ascribes the phenomena to a supposed great Atlantic wave or transient flood, of which one part swept across the low lands of Scotland, while another part was turned back by the mountains,—that in the district between the Clyde and the Spean, where the largest and best marked groovings were observed, there is satisfactory evidence to prove, that they were produced by bodies of vast depth occupying the valleys, moving from the mountain group as a common centre, toward the coast and the Lowlands in all directions, and exerting an immense force of pressure vertically and laterally,—that this quaquaversal motion, as well as the form, position, and size of the groovings, are conclusive against the idea that they were caused by currents of water loaded with stones and gravel, since no collected mass of water exists, or could exist, of the requisite magnitude and elevation, to send out streams in all directions capable of acting powerfully at the height of a thousand feet or more above the bottoms of the valleys,—that the effects mentioned, therefore, can only be accounted for by the agency of glaciers, as exemplified in the Swiss Alps.

The author began by stating, that during a calm, when the rain-drop was under the influence of the centripetal force only, the form and position of the rain-gauge were unimportant. The case, however, was widely different when the drop was likewise influenced by wind, for then any object raised above the surface, such as a rain-gauge projecting three or four feet from the ground, occasioned deflections and eddies, whereby the regular fall of the rain into the collector was prevented. The Author then recommended, that in all cases the gauge should be placed on the ground, with its mouth on a level with a regularly trimmed grass plot, so as to prevent eddies and evaporation.

After stating the case distinctly, and dwelling emphatically on its importance, as shewn by individual instances in private life, and by the statistics of the world at large, the author proceeded to describe the various methods adopted at present in India, and shewed their incapacity to meet the end proposed, as they merely agitated the air already in a room, or perniciously overloaded it with moisture.

The object of this communication was to lay before the Society a few characteristic incidents concerning Dr Black, gathered from Mrs Elizabeth Wordsworth, who was a servant in his household during the five last years of his life.

The facts recorded do not admit of abridgment, but they completely confirmed the accounts contained in the published biographiesof Black, concerning his valetudinarian and methodical habits, whilst they gave no countenance to the statement which had been credited in some quarters, that the great chemist was an avaricious or penurious man.

The object of this notice was merely to call attention to the importance of observing the phenomena of shooting-stars more carefully and rigidly, and of applying to them more correctly than has generally been the case hitherto, the measurement of time and of space, and to exemplify what may be done in this way by the calculation of a recent instance. This instance, the rare one of an ascending shooting-star, was furnished by Captain W. S. Jacob, Bombay Engineers; and he having given the place where the body first appeared, that where it disappeared, and the time, the author of the paper, who had great faith in his friend's exactitude, considered the opportunity favourable for trying what results would be given by the application of Sir J. Lubbock's theory.

The author placed on the table a battery of four pairs, each consisting of a rod of coke 2½ inches long by 1½ in diameter, surrounded by a cylinder of amalgamated zinc, 2½ inches high by 2¼ inches in diameter; the different pairs were firmly attached to the same bar of wood, and could be immersed in jars of stoneware at once. The arrangement was charged with a mixture of nitric acid one part, sulphuric acid four parts, water eight parts. The author stated that he considered the power of the battery, which was twice that of Grove's, was due to the heat generated on the surface of the zinc by the local action of the nitric acid.

About thirty years ago a species of manna, obtained from the Eucalyptus Mannifera, was brought from New South Wales, and was examined by Dr Thomas Thomson, and afterwards by Professor Johnston, both of whom ascertained it to contain a new species of sugar, different from the mannite which exists in ordinary manna. The author had, through the kindness of Mr Sheriff Cay, an opportunity of examining a very different species of manna, remarkable both from its chemical constitution, and from its possessing a definitely organised structure. This substance was discovered by Mr Robert Cay in 1844, in the interior of Australia Felix, to the north and north-west of Melbourne, where it occurs at certain seasons on the leaves of the Mallee plant, Eucalyptus Dumosa, and is known to the natives by the name of Lerp.