201 
At the evening meeting Mr. Holmes, of Leeds, exhibited 
and explained a Safety Lamp, in which he had introduced a 
modification of the principle of Upton and Roberts' lamp, 
without being aware of what had been previously effected by 
other parties. Mr. Holmes's plan was, however, an improve- 
ment, inasmuch as it contained an apparatus for regulating 
the admission of air. The thanks of the Society were voted 
to Mr. Holmes for his communication, and he was earnestly 
recommended to continue his experiments. 
The following paper was then read : — 
OBSERVATIONS ON THE OCCURRENCE OF BOULDERS OF 
GRANITE AND OTHER CRYSTALLINE ROCKS IN THE 
VALLEY OF THE CALDER, NEAR HALIFAX BY JOSEPH 
TRAVIS CLAY, ESQ., OF RASTRICK. 
The subject of drifted boulders has latterly very much 
engaged the attention of geologists, and as there is great 
diversity of opinion regarding the means by which they have 
been removed into their present situations, every additional 
fact which may throw light upon the subject is valuable. 
I was therefore much interested in hearing from Dr. 
Alexander's paper on the geology of the parish of Halifax, 
that in prosecuting the works on the line of railway, some 
blocks of granite had been found near Hebden-bridge, and 
this has led me to an examination of the bed of the river 
Calder, at Cromwell Bottom, about eight miles below the 
above-mentioned locality. 
At this place the valley expands considerably in width, 
and the river, winding from side to side, exposes a good 
section of the strata through which it passes. The stream 
has cut through a deep alluvial soil, about six feet in thick- 
ness, beneath which is a bed of large pebbles, containing 
some boulders of considerable size, the majority of which are 
of coarse-grained sandstone from the millstone grit series, 
B 2 
