The acquisition by the Cambridge Mineralogical Museum of a series of well-crystallized specimens of chalybite, raised within recent years from the mines in the neighbourhood of Camborne in Cornwall, afforded a favourable opportunity for an investigation of the chemical composition and optical characters of this substance. This seemed the more desirable since no analysis of the chalybite crystals from the Camborne district appears to have been published, and our knowledge of the optical characters of the substance is confined to some observations of Ortloff on material containing large quantities of manganese carbonate from Wolfsberg in the Harz.

In the summer of 1896 the Oxford Museum was enriched by a fine series of about eighty mineral specimens from a newly opened quarry at Haddam Neck in Connecticut, which were kindly presented by Mr. Ernest Schernikow of New York.

The species included in the series are green and pink tourmaline, albite, microcline, green and pink apatite, brown fluor, beryl, quartz, cookeite, lilac lepidolite, greenish-white muscovite, and a peculiar pink fibrous variety of the same mineral. To these must also be added, as occurring at the same place, green fluor, microlite, and columbite.

The locality is described as Haddam Neck, a village opposite to Haddam, on the other (eastern) bank of the Connecticut River, which is here about half a mile wide.

Of the various methods employed or suggested for the graphical representation on a plane of points on the surface of a sphere, the most important to the crystallographer are the stereographic and the gnomonic projections. Both are in common use, and both have their particular advantages. Professor Penfield has recently published a series of papers in which he points cut the advantages that accrue from the employment of the stereographic projection both in crystallography and cartography. He has devised protractors and scales, which facilitate the construction of the projection of the poles of the faces bounding a crystal or of portions of the earth's surface, and enable the angles between points or contained by zones, i.e. great circles, to be readily determined from measurements on the plane diagram.

On January 25th, 1899, at 7.54 a.m., a loud noise as of an explosion was heard at the settlement of Zomba, British Central Africa, and for many miles around ; almost simultaneously therewith, several small stones were seen to reach the earth in the neighbourhood of Zomba and were collected by the observers of their fall.

Mr. Alfred Sharpe, C.B., His Majesty's Commissioner and Consul. General for the Protectorate of British Central Africa, Mr. J. F. Cunningham, Secretary to the Administration, and Mr. J. McClounie, the Acting Collector of Revenues, on hearing the detonation, surmised that it had an origin in the entry of a meteorite into the earth's atmosphere, and with praiseworthy zeal and energy at once proceeded to collect, by aid of the telegraph and by personal interviews with the witnesses, all the reliable evidence that could be obtained relative to so extraordinary a phenomenon.

The specimen to which the following note refers was found in the Oxford Collection, and nothing is known of its origin.

It is a polished piece of translucent emerald-green stone, with patches of darker green and also patches of a dull brown colour.

The stone has taken a high polish, and brilliant internal reflections from immediately below the surface of the paler portions give it in those parts almost the appearance of a flawed emerald. But the fractured surface shows it to be merely a massive, pale green, micaceous mineral with brown patches, which appear at first sight to be only an iron-stained variety of the same substance.

The validity of Haüy's great law of the rationality of intercepts — better known as the law of rational indices—or its equivalent, the law of homogeneity of arrangement of the ultimate particles in a crystalline structure, has as yet never been seriously called into question : nevertheless, in the crystals of the telluride of gold, calaverite, we find characters which are to all appearance at variance with this law. As far as the author is aware and can ascertain, no difficulty of a precisely similar kind has ever been encountered before. Certain substances do, indeed, display the so-called optical anomalies; but these are, as was first established by Mallard, in reality in strict accordance with the actual crystalline arrangement.

The molecular volumes of the members of an isomorphous group of minerals in general show an approach to equality. In other words, minerals having an analogous chemical composition show not only closely related crystalline forms, but have also approximately equal molecular volumes. Many years ago J. D. Dana endeavoured to show that a simple relationship as regards molecular volume also subsisted in the case of various minerals which were closely related crystallographically, although unlike chemically. He concluded that in these cases the similarity in form depended solely on the relationship in molecular volume, and had nothing whatever to do with the chemical composition.

It is somewhat remarkable that a group of minerals, of which such excellent transparent crystals are known as of pyromorphite, mimetite, and vanadinite, should not have hitherto been submitted to a detailed optical examination, except as regards the nature of the interference figures visible in a cross-section. The only reference to the refractive indices of these substances, which I have been able to find, is one by Schroeder van der Kolk, who states that those of pyromorphite amt vanadinite are above 1.93 (as found by immersion in highly refracting liquids), and that they have a birefringence of 0.02 and 0.01 respectively.

Minerals containing iodine as an essential constituent are of rare occurrence in nature. The most common, and that first described, is silver iodide, which was analysed by Vauquelin in 1825; hexagonal crystals of iodyrite were described by Des Cloizeaux in 1854. Other iodides are marshite and the new mineral miersite ; iodobromite and schwartzembergite also contain considerable amounts of iodine. The existence of mercury iodide seems to be doubtful; the supposed mercury iodide from Broken Hill consists of an intimate mixture of cinnabar and iodyrite. Two iodates are also known, namely lautarite and dietzeite.

Mode of Occurrence.—This new mineral was discovered at Gangapitiya, near Ambakotte and about 12 miles east of Kandy, Ceylon. In this locality quarries have been dug for the well-known Ceylon moonstone, which occurs in large porphyritic crystals in an acid granulite.

Bands of this granulite, which is composed mainly of quartz and felspar in finely granulitic and occasionally graphic structure, alternate with bands of limestone up to 18 inches wide. Between limestone and granulite occur contact-zones consisting, next to the limestone, almost entirely of a coiourless diopside, but near the granulite of a mixture of diopside with other minerals, viz. blue spinel, a little apatite, occasionally scapolite or plagioclase, and the blue mineral which is the subject of the present note.

For this new mineral I propose the name baumhauerite in honour of Dr. H. Baumhauer, Professor of Mineralogy in the University of Freiburg, Switzerland, who has done so much to elucidate this complicated group of sulpharsenites of lead.

System: Oblique. a : b : c = 1.136817 : 1 : 0.947168; β = 82° 423/4.

These elements are calculated from the angles 100 : 101=50° 27′ 101:001 = 32° 153/4′ and 010 : 111̄ = 50° 33′ measured on crystal No. I.

The crystals closely resemble dufrenoysite and jordanite in appearance. They may be distinguished from dufrenoysite by the marked oblique development of the zone [100,001], and from jordanite by the absence of twin striations and by the colour of the streak. The edges in the pyramid zone and between planes in the zone [100,010] are more or less rounded.

The following notes on the petrology of British East Africa are the result of an examination of rock-specimens collected by Professor J. W. Gregory on his well-known expedition from Mombasa to Mt. Kenya and Lake Baringo in 1892-3, and of rock-collections from the Uganda Protectorate which have been recently presented to the British Museum by Sir Harry Johnston.

The collections include examples of the Archaean gneisses, schists, and granites which constitute the prevailing basement rocks of Central Africa; of ferruginotls schists, coarse sandstones, and quartzites belonging to the Palaeozoic Karagwe series ; and of an interesting series of Tertiary volcanic rocks comprising phonolites, phonolltic traehytes, riebeckite-rhyolites, kenytes, and basalts from the volcanoes of the Great Rift Valley, as well as of nephelinites and basaltic rocks containing melilite and perofskite from Mr. Elgon.

Very little is known of the crystalline form of thc somewhat rare mineral stannite, since in the few localities in which it has been found it usually occurs only in the massive state. Several suggestions, summarised below, have been made as to the type of crystalline symmetry of the mineral, but hitherto no crystals have been completely examined.

• (1) Orthorhombic. Haüy (1822), from an examination of cleavage fragments from Cornwall, concluded that the primitive form might possibly be a right rhombic prism.

• (2) Cubic. Haidinger (1825) mentioned Cornish crystals, having apparently the form of regular cubes, but the dulness of the faces did not allow of any measurements. The massive material appeared to show cleavages in the directions of the faces of the cube and rhombie dodecahedron. (Crystals of Cornish stannite are further mentioned on p. 65 below.)

The crystals to which this note refers, occur in a quarry in the New Red Sandstone at Bindon, in Somerset, on the property of Mr. H. H. Worthington, and were presented to the Oxford Museum a few months ago by his son, Mr. J. H. Worthington. I have lately had an opportrinity of visiting the locality and examining the mode of occurrence of the specimens.

The crystals have all been obtained from a single, roughly vertical vein in the side of the quarry, which shows an exposure of irregularly alternating beds of red sandstone and conglomerate. The pebbles of the latter consist, for the most part, of a compact purplish limestone, while a few are of greasy-looking quartz.

The mineral described below was found by the present writer, in the year 1893, at Kodikanal on the Palni Hills, in the Madura District of the Madras Presidency. These hills, which rise at Kodikanal to a height of 7000 feet above the sea, form a range some thirty miles long in a WSW.-ENE. direction, with a breadth about half as great. They are composed of grey igneous rock, belonging to Mr. T. H. Holland's ‘Charnockito’ series, the slight foliation being in a direction coincident with that of the range, while the dip is at high angles. The mountains are at present mostly clothed with grass only, the soil being highly Charged with peaty matter, and moderately fertile.