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is pressing outwards or towards the flanks. 2. That they have been caused 
by earthquake-shocks, perhaps very long since. 3. That the y are the out- 
ward expressions of faults slowly taking place, and represent much greater 
disturbances or shifts at considerable depths. I can conceive,” he says, 
of no other theories than these to account for their formation. Let us 
consider their respective merits. With regard to (1) the facts that the 
mountain-s/f?e has no slipped appearance, and that the fissures often occur 
on a more or less flat-topped mountain, are against this supposition, though 
the ease with which one can imagine a great slip inclines one rather 
naturally towards it. That (2) is a possible cause no one will deny, though 
in this case it seems almost strange that the fissures should not be more 
frequent than they are, seeing that the shocks must always have been more 
or less felt over so small a district whenever they occurred strongly at one 
part. Against (3) an objection might be raised that they occurred only 
among certain rocks of the district, whereas faults would be likely to be 
found without any such marked restriction. But I do not think such an 
objection would hold; the non-occurrence of the fissures of this class 
among the Skiddaw Slate mountains is probably due to the nature of the 
rock ; if fissured gradually, or even suddenly, the readily splintering and 
shivering slate would close the crack almost directly, so that it would 
be unperceived, whereas among the hard and hlocky rocks of the Volcanic 
Series the fissure would stand open, or have large angular blocks wedged 
in it.” 
The Structure of Crinoids. — Mr. J. Rofe, F.G.S., has published a 
capital paper on this subject. He says that through the kindness of 
Mr. E. Hollier he has procured pieces of columns from the Silurian 
formation at Dudley, including Taxocrinus, Pei'iechoerinus, ActinocrimcSy 
MarsupioerinuSy Cyathocr'inuSy and two columns undermined, as they 
were without heads. Of these he has had slices mounted for the micro- 
scope, and finds on examination that, although there appears to be a general 
similarity in construction with the round columns of the Mountain Lime- 
stone, as they are more metamorphosed by crystallisation, the details are 
more difficult to distinguish. Some of them exhibit pentaphylloid sections 
of the central canal, as the Taxocrinm and Cyathocrinus, whilst the Mar- 
supiocrinus shows a rosaceous section, the petals being wide and the 
divisions between them forming very acute angles ; but he cannot satisfac- 
torily make out the fibro-cartilaginous structure round the canal, though, 
from appearances, it is probable that it would be found by further examina- 
tion with a great number of specimens. This paper, which is of some 
length, will repay perusal. — “Geological Magagazine,” June. 
MECHANICS. 
Improvements in Lamps for Living Operations. — It appears that M. Pas- 
teur has discovered that the vitiated air discharged by divers contains 
oxygen enough to support the flame of a petroleum lamp. He accordingly 
connects, with the flexible escape-pipe of a diver’s helmet, a suitable lamp 
of the above description. The lamp may be carried in the hand of the diver 
