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POPULAR SCIENCE REVIEW. 
lakes were hollowed out by the ice. The lakes are deepest at that eud 
nearest the glacier, and in many cases their size and depths were shown to 
he proportionate to the size of the ice-stream. 
Figure 5, is a greatly reduced figure of the Seelidosaurus, briefly noticed 
in the last number. Nothing further need be added, except to call atten- 
tion to the reptilian character it shows well, with which most of our 
readers will be familiar, of having the lower jaw made up of several bones 
on each side, instead of one as in mammals. The hollow articulation of 
the lower jaw with the ball in the skull, which contrasts so with the 
reverse of the structures in the mammal, is unfortunately not shown. 
HAT wonderful work of engineering enterprise, the Mount Cenis 
Tunnel, is at last making satisfactory progress. Its entire length is 
to be 7-9 miles, and it presents the peculiar difficulty, that from the 
immense height of the mountain above it, no shafts can be sunk, and the 
whole has to be excavated at two working faces. At the beginning of last 
year boring machinery was applied, worked by compressed air ; it con- 
sisted of eight drilling machines, making 200 strokes of G inches per 
minute ; 70 holes about 3 feet deep were thus made in the face of the rock 
in six hours, and four hours were employed in blasting and clearing away 
the fragments. According to the latest accounts a new steam-machine has 
been applied, the invention and manufacture of Messrs. Hawkes, Crawshay, 
and Co., resembling a small locomotive engine, and carrying a large wheel 
on which are fixed a series of steel cutters intended to bore auger fashion 
into the rock, whilst the fragments dislodged are removed by rakes attached 
to the machine. 
During March important experiments were made at Shoeburyness by 
the committee on iron plates, to ascertain if wood backing could be dis- 
pensed with in iron-cased vessels. The target had been constructed for 
the committee by Mr. Fairbairn, and consisted of 4-|-inch armour plates of 
rolled iron, attached by 2-inch bolts to sheathing plates one inch thick, and 
these in turn riveted to very strong iron ribs. The armour plates were 
not dovetailed as in the Warrior, but depended entirely on the bolts, which, 
as the result showed, completely failed, the concussion breaking them 
in a most extraordinary way. The armour plates were therefore left at 
the mercy of the shot, buckled forwards, and might have been displaced if 
the firing had been continued. On the edge of two plates, that is, at the 
weakest part of the target, three of the heaviest Armstrong shot struck 
successively on the same spot, and the target was penetrated. 
I N offering to the readers of the Popular Science Review a resume of 
what has been done in microscopical science during the past few months, 
it must be borne in mind that a selection only can be made from the most 
MECHANICAL SCIENCE. 
MICROSCOPICAL SCIENCE. 
