PROCEEDI^'GS, 1859 — 1870. 
339 
a very great pressure. They show the spoutaueous movement of the 
bubbles which they contain extremely well. The description is given 
of specimens taken from different parts of the cooled mass, which 
show no kind of similarity with the natural rock. Where it does 
reseml)le a natural rock it is more like basalt than granite, and its 
structure is identical with some of the stony masses obtained by 
fusing basalt or basaltic lavas. He was led to the conclusion that 
the natural rock, before being crystallised, was in a very difterent 
condition to the artificial state after melting, which is especially 
shown by the fluid cavities in the q'lartz. This water, and the intense 
pressure under which the rock was formed, are features which the 
author had been unable to imitate in the artificial product, but he 
contended that such experiments, and the microscopical examination 
of the resulting masses, were likely to lead to a far better knowledge 
of the igneous rocks than we at present possess. 
Mr. Denny described a fossil plant which had not hitherto been 
noticed, from the Carboniferous Sandstone near Leeds. It was 
apparently the terminal portion of the root of a plant resembling 
Stiginaria, but differing from it in the scars being elevated above the 
surface, and of a lozenge-shaped pattern. 
Mr. Phillip Cooper read a paper at Huddersfield on the effects 
of certain geological arrangements on the working of Coal. Contrary 
to a generally received opinion he considered that faults were bene- 
ficial in draining the water from the strata, and thus preventing a 
large expenditure of money in pumping. He cited a number of 
instances where a bed of coal became divided by intervening strata, 
sometimes to a very large extent; due, according to Sir Charles Lyell, 
to a slow settling of a part of the area of the coal bed after a lower 
portion had been deposited, together with a subsequent deposition of 
shale, etc., of which they are formed. He concluded by stating the 
difficulty there will be in working very deep beds of coal, from the 
great increase of temperature. At a depth of 4,000 feet the tempera- 
ture would be 100 to 1 20 degrees, and hitherto the experience in 
ventilating mines had been that very Httle difference in temperature 
was produced by the influx of fresh air. 
In March, 1865, ^Slr. T. W. Embleton, of Middleton Colliery, 
