PROCEEDINGS, 1859 — 1870. 
341 
was, from time to time, alternately raised and depressed, and beds of 
sand and mud in large quantities were carried into it, the result being 
the aggregation of the Yoredale Series and the ^lillstone Grits. The 
Coal Measures resemble the latter to some extent, but the sandstones 
are less coarse and persistent, and workable beds of coal are numerous 
and important. The fact that each of these required for its forma- 
tion a land surface shows that during the coal measure period the 
oscillation of the sea-bottom was more pronounced than during the 
millstone grit times, and this is, no doubt, the reason for the gTeater 
subdivisions of the beds. The physical characteristics of the surface 
of the district, due to the peculiar characters of the underlying rocks, 
were described. The more or less tame and monotonous flats, with 
large rolling hills of ^fountain Limestone ; the gentle slopes on the 
one hand, and precipitous edges on the other, of the Millstone Grit ; 
and the softer and more undulating scenery of the Coal Measures: are 
each characteristic of the rocks of which they are composed. 
Mr. John Hutchinson, of Barnsley, gave the result of some 
observations on Fire Damp and Safety Lamps, and the circumstances 
under which the fire damp will explode. A number of experiments 
are described which had been made in conjunction with Mr. Wilson, 
of the Driffield Lane Colliery, and ^Ir. Minto, of the Mount Osborne 
Colliery, to show the comparative merits of the different kinds of 
Safety Lamps. A rectangular box was constructed 1 2 feet in length, and 
11 inches by 4 inches inside. This was inserted into a flue in connec- 
tion with the chimney shaft to obtain a current of air. The velocity 
of this current was regulated by a small sliding door near the inner 
end, and a second sliding door about the centre was provided of suf- 
ficient size to admit a Safety Lamp. A service pipe of coal-gas was 
connected by means of an india-rubber tube, and allowed to play into 
the end of the box, tlie amount of gas and the force of the current 
of pure air being regulated at pleasure, so as to produce a miniature 
working of a pit in which an escape of gas may be found. With the 
current of air passing through the box at the rate of five miles an 
hour, not an uncommon velocity in a pit, the following comparative 
results were obtained : — The Davy Lamp exploded in five seconds ; the 
Mousarde in six ; the Clanny in 12 : the Belgian in 18 ; and the 
