After seeing in the course of one of Sir W. Thomson's lectures an experiment showing the contraction which takes place when a solution of common salt is mixed with water, I resolved upon making a number of experiments with a view to noting the result of mixing various solutions.

In October 1881 I published in the Quarterly Journal of Mathematics (xviii. pp. 110–149) a “List of Writings on Determinants,” which contained the titles of all the books, pamphlets, memoirs, magazine articles, &c, which were then known to me to exist on the subject of the Theory of Determinants. The list consisted of 489 entries arranged in chronological order, the first date being 1693, and the last 1880. During the three years which have elapsed since it was published, I have been steadily making manuscript additions to it, not merely in the way of continuation for the purpose of keeping it up to date, but also by the intercalation of omitted titles unearthed in the course of my own researches, or brought to my notice by obliging correspondents.

This paper is the outcome of 12 months' private spectroscope building, two months' observing therewith, and ten months' computing and graphical presenting of the observations. The result is a Solar Spectrum map, extending through so many as 60 double quarto plates, but capable of being arranged for the cheapest photolithographic reproduction, in a manner very easy to examine, convenient for reference, and yet at the same time affording at every point new and severe tests for its degree of accuracy.

It may be within the recollection of the Fellows of the Society, that in December 1883 I had the honour of reading, in this room, a paper on the Madi Tribe of Central Africa.

The paper which I have the honour of presenting to you to-night is similar in construction to those I have previously brought under your notice on the For and Madi Tribes.

The Waganda are very different from the tribes further north, and a description of them will I think aptly illustrate the very marked contrasts presented by the various Central African Tribes.

Etectro-Chemieal Reactions between Metals in fused Salts.—The present communication contains some results of a furthur study of electrical reactions at high temperatures in fused salts.

The interchanges of electro-chemical position between such metals as platinum and copper and platinum and iron in fusing salts, noticed by the author, led to an investigation as to the effect on the metals of varied intensified temperature in different parts of the same fusing salt.

During the course of an investigation on the cerite metals we found that peroxide of hydrogen, added to the precipitated hydrates in presence of excess of alkali, is a very delicate test for cerium, even in presence of Lanthanum and Didymium, owing to the formation of a dark yellow or brown compound, probably a peroxide, which differs from that produced by chlorine under the similar circumstances.

It is rather remarkable that the Decapoda should have yielded fewer new forms than the Octopoda, although judging by the number of genera contained in them, the former is a much more extensive group than the latter, and is furthermore represented by a larger number in the “Challenger” collection, as the following synopsis will show :–

I. When the straight lines forming the sides of the figure are referred to two given straight lines at right angles in the plane of the figure–without reference to the co-ordinates of its angular points.

The study of the development of the herring, of which the following pages contain the first results, was commenced at the beginning of last August. At that time I went to a small fishing village called Sea Houses, North Sunderland, on the Northumbrian coast, and obtained a large number of herring ova, which I fertilised artificially on glass plates when on board a herring boat off the Longstone Lighthouse.

My attention was first drawn to the change of volume which takes place when a salt is dissolved in different quantities of water, by an experiment shown by Sir William Thomson in his class at the Glasgow University. He took a wide glass tube, about 3 feet long, sealed at one end, and having a narrow tube attached to the other end. The lower half of this tube he filled with a saturated solution of common salt, and on the top of that he placed a layer of water, which just reached a mark about the middle of the small tube. He then corked the open end, and mixed up the water and brine by inverting the tube two or three times, when it was seen that the solution had contracted.