TRANSACTIONS OF THE SECTIONS. 89 
rhombic octahedron, whose three axes have the relation of p} m? 
t. Mr. Griffin entered into various details to prove that the occur- 
rence of planes, not representable by one or other of these seven forms, 
was a mathematical impossibility, and that the proposed system of no- 
tation was amply sufficient for all the purposes of the chemist and 
mineralogist, while it had over other systems of crystallography the ad- 
vantage of requiring but a small amount of mathematical knowledge. 
Prof. Jacobi made some observations respecting his discovery of 
Galvanoplastics, or electrotype, from which, and from printed docu- 
ments, it appeared that he had communicated a notice of the discovery 
to the Petersburgh Academy on the 5th of October, 1838. In his 
pamphlet, ‘ Die Galvanoplastik,’ the date of this communication is 5th 
of October, 1839; but it was stated that this was a typographical 
error. The first published account of the discovery appeared, accord- 
ing to Prof. Jacobi, in a Petersburgh journal of the 30th October, 
1838*, 
GEOLOGY. 
On the Coal Formation of the West of Scotland. By Mr. J. Craic. 
Mr. Craig had surveyed this district at the suggestion of the Local 
Committee of the British Association in Glasgow. After describing 
the general features of the district, and the character of the superficial 
deposits, and mentioning that he had found the Mytilus edulis, the 
Litiorina littoralis, and other recent sea-shells at the elevation of 360, 
100, 80, and 40 feet above the present level of the sea, Mr. Craig pro- 
ceede to describe the different portions of the strata, as subdivided 
and coloured in the Map and Sections. These he classed as follows :— 
Ist. The upper red sandstone series. 
2nd. The upper or fresh-water coal series. 
3rd. The upper marine or limestone series. 
4th. The lower coal series. 
5th. The lower marine limestone series. 
6th. The old red sandstone. 
Ist. The upper red sandstone, consisting of red and variegated 
sandstones, shales, some thin seams of coal, and a very few traces of 
coal plants, extends over very considerable portions of the regular coal 
beds both in Lanarkshire and Ayrshire. On the south of the deposit 
in Lanarkshire, it appears not to be conformable with the upper coal 
series as on the north, but occurs in actual contact with some of the 
* Der St. Petersburger deutschen Zeituug. 
