The samples analysed came from the bottom of a small loch. No. 1 was of a yellow-gray eolour, even in texture, and readily broken down between the fingers.

No. 2 was distinctly red, and marked with dark spots. It broke down readily, and was more dense than No. 1.

No. 3 sample was red in colour, with dark brown and red particles throughout the mass.

The part played by hornblende (i.e. the monoclinie amphiboles) in the constitution of rocks, and the relation of that mineral to angite (including all the monoclinlc pyroxenes), are subjects which, in recent years, have occupied much attention. It has been recognised that the early notions of paragenesis cannot be applied, without many reservations, to rock-forming minerals. Some petrologists have gone so far as to suppose that augite and hornblende "are two different crystallographic forms of essentially the same molecule, of which the former is most stable at high, the latter at ordinary temperatures." If this view receives any extensive confirmation, the well-known conversion of angite into hornblende must be regarded as a purely paramorphic change due to altered conditions.

The following new localities for these t~ree rare minerals have lately come under my notice.

I was some time ago presented by George Moodie, Esq., formerly Surveyor-General to the Transvaal Government, with a specimen which he obtained himself from the lead mines at Marico Zeerut, near Potsehefstroom, in the Transvaal.

This specimen was part of a small druse which is lined with crystals in a corded arrangement. These crystals appear to me to be zinc carbonate.

Superimposed thereon there are crystals of both linarite and of caledonite, and also minute crystals of an emerald-green mineral which is unknown to me.

There being but one specimen, I do not desire to remove any of the last for testing.

This mineral is found as a constituent of a variety of gabbro occurring on the shore at the village of Coverak, Cornwall. The rock is an aggregate of allotriomorphic grains of chrome-diopside, labradorite and olivine. The olivine is, in general, perfectly fresh, but it is traversed by a network of veins in which magnetite has been deposited. The whole of the iron-ore present in the rock occurs in these veins in the olivine ; so that in this, as in other respects, the rock bears a close resemblance to some of the gabbros described by Prof. Judd from the Western Isles of Scotland.

Few mineralogical problems are of greater interest at the present time than those connected with the metamorphism of rocks. We are called upon to determine the exact series of processes by which a rock, having a particular texture and consisting of certain mineral species, is converted into a totally dissimilar rock, possessing, not only a different structure, but a distinct mineralogical constitution.

At a meeting of the Cambridge Philosophical Society on May 20th, Mr. Robinson read a preliminary paper "On the formation of Struvite by Micro-organisms."

"The author had observed the formation of fine well-formed crystals in many tubes of nutrient gelatin and agar-agar, in which he was growing pure cultivations of various micro-organisms."

It is my unpleasant duty this evening to retire from the honourab!e position in which I was placed by the members of the Mineralogical Society three years ago. Before doing so I would say a few words on a subject which has demanded grave consideration from myself, and doubtless also from my predecessors in the Chair : namely, as to whether any formal address should be delivered by your President during his term of office.

Some little time ago I observed very large and fine specimens of gyrolite among a number of zeolites which a friend had lately received as a gift, from the cuttings on the railway from Bombay to Poonah—the locality for the fine apophyllites. These occurred in specimens much larger than those in which the mineral is seen in Iceland, Faröe, or Scotland.

This substance was found by Mr. Dudgeon at the Pibble mine, which is directly opposite to Cairnsmore of Fleet, in Kirkeudbrightshire, and is within a few miles of Creetown.

This mine was worked for lead, and a few pieces of copper-nickel (nickeline) were obtained at it. The blue variety of the silicate of zinc also very sparingly occurred, and there were slight appearances of the phosphate and of the carbonate of lead.

In a list of the known falls of meteorites published by Meunier in 1884, is a record of the fall of a meteoric stone at Chartres, Eure-et-Loir, France, in September 1810, and as authority is quoted the catalogue of the meteorites of the Muséum d'histoire Naturelle at Paris. No stone of that name is mentioned in the printed list of the Paris collection published in 1882, but according to a later manuscript five grams were in the Museum in the year 1885. The authenticity of the fall is accepted in the lists since published at Vienna and at Harvard College. No representative of the fall, however, appears in any other list of the better known meteorite collections, and it seemed that only the fragment at Paris had escaped destruction. Lately, however, on receiving from Professor Lewis a manuscript list of the meteorites under his charge, I was agreeably surprised to find that a piece weighing no less than 60 grams of a Chartres stone was in the Cambridge collection. The specimen and its label were sent to me for inspection, and they suffice in my opinion to prove that the Chartres fall of September 1810 is mythical, and owes its origin to a simple error of memory.

A Remarkable series of crystallised calcites from Cumberland which have been found during the present year deserve description, both on account of their size and beauty, and also by reason of their peculiar form.

The crystals, although obtained from a small area, exhibit great variety of habit and appearance, and fall naturally into the seven groups which are described below. Of these the most remarkable consists of a series of magnificent heart-shaped twins, somewhat similar to the rare but well-known "butterfly twins" of Eyam, in Derbyshire; they result from the same mode of twinning as the latter, but are far larger and more beautiful than any of the Derbyshire twins, frequently measuring four inches in breadth. There are also crystals which exactly resemble the true butterfly twins of Eyam, and others which arc very similar to the rectangular twinned prisms of Wheal Wrey in Cornwall. A second and very rare twin law is also represented among these specimens, in which the rhombohedron, whose edges are truncated by the cleavage planes, acts as twin-plane.

This mineral Occurs in thin hexagonal plates with bevilled edges, which were formerly referred to the rhombohedral system, on account of their characteristic triangular striations, which run parallel to alternate edges of the hexagon.

Des Cloizeaux in 1867 (Nouvelles Recherches, p. 85) found the crystals from Freiberg, which are sometimes sufficiently thin to transmit light, to be biaxal, the acute bisectrix being perpendicular to the surface of the plates; the apparent angle between the axes could not be determined accurately, but was found to vary from 63° to 88°. The mineral must consequently be regarded as orthorhombic, with a prism angle very near to 60°.

In the basaltic lavas of Iceland certain porphyritic crystals of unusually large dimensions, occur embedded in the matrix of the rock, and from an early date have received the notice of writers on the geology of that island. Amongst these authors might be mentioned :—Professor Forchhammer, Dr. F.A. Genth, M. A. Damour, Prof. Zirkel, M. P. Schirlitz, and M. R. Bréon.

Many years ago I requested Mr. Swift to make for me a first-rate Binocular Petrological Microscope. The centering of the stage by screws was, I suppose, as good as it could be made. I found it unsatisfactory when using high powers on small crystals. A centering nose-piece answered no better. Only by the simultaneous rotation of the polariser and analyser by hand, little by little, could I keep the interference figures of small crystals in the field of view, or feel certain that the figures had not left it during rotation owing to the excentricity of the centering.