In continuation of the observations into the condition of the water of frozen lochs, which were communicated to the Society at the meeting of the 20th January 1879, I have been able to repeat the observations in Linlithgow Loch on two separate days, and also to visit Loch Lomond. The observations in Linlithgow Loch were made on the 25th January and 1st February, both times at the same spot, from which the Court House Flagstaff bore N. 150½° E., and the Rickles Island N. 63½° E., the depth being 48 feet. On the 25th January there was a diminution of pressure under the ice, so that when it was pierced the air rushed in with a roaring noise for about a minute, when it stopped, and the water rose in the hole. On the 1st February, on the other hand, the ice was cracking and resounding on all sides, and water rose at once in the hole when the ice was pierced, there being at the same time a considerable escape of air. These two stations have been numbered respectively 6 and 7; they are exactly in the same spot, a few yards distant from that of No. 4. The ice was very decidedly thicker than it had been.

Thermometers were placed throughout the hall, one on each of the four walls, 6 feet from the floor, the one on the south wall being a couple of feet below the inlet for the hot air. Three were placed along the centre of the roof, 2 feet or so under the roof. In the stove-chamber, first one and afterwards two stoves were placed, with double smoke-pipes before entering the chimney.

In this Chapter, Dr Heddle discussed the substances usually thrown together, under the term of Chloritic Minerals. He showed, by an extensive series of analyses, that they were to be divided into three groups—those which occurred in metamorphic rocks, in recent strata, and in volcanic rocks.

He proposed to confine the term Chloritic to the minerals which are found in metamorphic rocks, and to apply the term, the Saponites, to those which occur in volcanic rocks.

For the purpose of observing the temperature of the waters below the surface in lakes and seas, two classes of thermometers have been used—namely, ordinary thermometers and self-registering ones. The earliest observations were made with the ordinary thermometer, and it was used in one of two ways—either it was sunk itself to the desired depth, and was so enveloped and protected by badly conducting material, that in bringing it up again through the layers of water of different temperature it had not time to alter its own temperature, or a quantity of the water at the desired depth was enclosed in a bucket of suitable construction and brought to the surface, and then immediately tested with the thermometer. Many very excellent and trustworthy observations exist which have been made in one of these ways.

In the process of making mercaptan by collecting the distillate from a mixture of ethyl-sulphate of calcium and sulphydrate of potassium, along with water and mercaptan, a considerable quantity of crystalline substance was observed to collect in the receiver, and also towards the end of the condenser. The receiver having been placed in a freezing mixture, to condense as much mercaptan as possible, it was thought that the crystalline substance was ice, and the freezing mixture was removed. The crystals, however, continued to be formed, and even stopped up the end of the condenser, so that it was necessary to pour in hot water to melt them. In a few minutes they were again formed, not only in the receiver, but half way up the condensing tubes, through which water at about 2–3° C. was running. As it was evident that these crystals could not be ice, the conditions under which they were formed, and their composition, were subjected to investigation.

The following measurements were made by means of a Gramme machine, recently procured for the University. I desired to make use of it, not only for electric light, but for electrolysis, the exciting of electromagnets, and various other purposes for which we have hitherto used from 4 to 40 or so Bunsen cells. I therefore arranged the driving-gear so that with the same motor (a 3½ h.p. gas-engine) it was easy to use either of three speeds. These are, approximately, 800, 533, and 320 turns per minute. The electromotive force varies, of course, not only with the speed but with the resistance of the whole circuit—falling off at first rapidly and then more slowly for any one speed, as the resistance is increased. As I had no means of measuring the speed directly, I was somewhat puzzled at first to find the electromotive force at any one speed rise to a maximum, and then rapidly fall off as the whole resistance was gradually diminished.

This is really Laplace's subject in his Dynamical Theory of the Tides; where it is dealt with in its utmost generality except one important restriction,—the motion of each particle to be infinitely nearly horizontal, and the velocity to be always. equal for all particles in the same vertical. This implies that the greatest depth must be small in comparison with the distance that has to be travelled to find the deviation from levelness of the water-surface altered by a sensible fraction of its maximum amount. In the present short communication I adopt this restriction; and farther, instead of supposing the water to cover the whole or a large part of the surface of a solid spheroid as does Laplace, I take the simpler problem of an area of water so small that the equilibrium-figure of its surface is not sensibly curved.

Dr Coats stated that this communication referred to part of an investigation on the physiological action of anæsthetics, undertaken, at the request of the British Medical Association, by Dr Ramsay, Dr M'Kendrick, and himself.

When the elements of the first row of a determinant are all positive integral powers of one quantity, the elements of the second the like positive integral powers of another quantity, and so on, the determinant is called an ALTERNANT; for example, .

Every alternant of the nth degree is evidently a function of n variables, viz., the n quantities whose powers are the elements. To interchange two of these variables would be the same as to interchange two of the rows of the determinant, and therefore would have the effect of merely changing the sign of the function. A function having this property, and therefore closely resembling a symmetric function, Cauchy called a symmetric function also distinguishing the two kinds as alternating and permanent.

Professor Blackie, after paying a high compliment to the erudition, ingenuity, and fine taste of the Aberdeen Hellenist, proceeded to give reasons why, in his opinion, the theory now broached, to the effect that certain books of the “Iliad” were composed by the author of the “Odyssey,” which author is to be considered as the real Homer, though not destitute of a certain plausibility, is untenable. The reasons were—(1.) The character of the minstrel as distinguished from the literary epos warrants the presumption that any small diversity in certain secondary characteristics of different sections of the poem, as we now have it, is a legitimate proof, not of diversity of authorship, but only of diversity of materials collected from different sources. (2.) The manner in which the minstrel epos was originally circulated, not as a separate literary composition to be read and studied, but as a sequence of easily separable cantos to be handed about and sung separately, rendered it, even when wrought into a finished artistic whole by the genius of a great singer, peculiarly liable to interpolations and variations of various kinds, which form no legitimate ground of induction with regard to the character or attitude of the original composer.

The Algebra of Logic, being the science of Necessity and Probability, supplies a variety of methods of great power for solving problems in the theory of Probability. I propose to bring before the Society a few examples extracted from my work on the “Principles of the Algebra of Logic,” which is about to be published. A large class of problems, some of which have created considerable diversity of opinion among mathematicians of eminence, can be solved by means of a single theorem.

The specimen which formed the subject of this memoir was one of three, imported into England by Mr Farini of London.

The skeleton being already well known, and the state of the parts preventing an examination of the muscular anatomy, attention was directed solely to that of the viscera, of which no complete description had hitherto been given. Drs Barclay and Neill in this country, and subsequently Professor Wyman in America, had previously investigated some points in the anatomy of the soft parts of Beluga, but their descriptions are so fragmentary as to necessitate a more accurate and extended investigation of the viscera.

The Committee had submitted to them Notes by the Convener of two visits to the West Highlands (including the Outer Hebrides) which he had made during the summer and autumn of 1878. These Notes, accompanied by diagrams of boulders and striated rocks, afford a large amount of information bearing on the subject of boulder transport, the direction of transport, and the agent of transport.

There has also been laid before the Committee a report by William Jolly, of Inverness, one of its members, “On the Transportation of Rocks found on the Shores of the Moray Firth;” as also Notes by Messrs Somervail and Henderson (Edinburgh), “On Boulders and Striated Rocks in the Pentland Hills.”

Along the south shores of the inner portion of the Moray Firth, certain movements of rocks have taken place in geological times which are interesting as bearing on the inquiry into the general transportation of boulders over Scotland. These rocks are, happily, of very distinctive varieties, which renders the question of their source and movements a comparatively easy one. On these, I beg to offer some rapid notes, in connection with the work of the Boulder Committee.