414 Progress in Sctence. [July, 
selection and careful training of the men employed, and especially, in a safety 
point of view, of engine-drivers and signalmen ; (2) by providing those men 
with reasonable and necessary apparatus and accommodation for the proper 
performance of their duties ; (3) by maintaining good discipline amongst 
them, which is only feasible when proper means and accommodation are 
provided, when proper modes of working are adopted, and when it is possible 
for them to carry out in praétice the rules and regulations furnished for their 
guidance. 
Dire@ly bearing upon this subject, also, were two papers read before the 
Institution of Civil Engineers, the one, ‘‘ Safety of Permanent Way,” by C. P. 
Sandberg, and the other on “ Railway Fixed Signals,” by R. C. Rapier. We 
can now only briefly refer to these two papers. In the former one, the prin- 
cipal object the author had in view was to draw attention to the weakening of 
rails caused by punching or notching. In the latter, attention was chiefly 
given to the interlocking and block system, and a tabular statement exhibited 
showed that, by introducing this system on fourteen of the principal railways, 
by an expenditure of } per cent on the whole cost of the railways, their 
carrying power might be so increased that three times as many trains could 
be run on the block system as without it, and with greater safety. 
Rock-Drilling.—With the ever-continuing increase in the progress of mining 
industries, the question of rock-drilling is gradually attaining an importance 
second to few others conneéted with the leading industries of the world. A 
paper on the subje@ of * Rock-Drilling Plant in its most Recent Modifica- 
tions,’”’ was recently read before the Institution of Mechanical Engineers by 
Mr. T. B. Jordan, the principal obje@ of which was to dire@& attention to the 
Darlington rock-drill, in which most of the defects of other drills were avoided. 
In this drill all the numerous small parts are omitted, and a machine has 
been produced that will make from 100 to 1ooo blows per minute under a 
pressure of from 4o to 50 lbs. per inch. Only two parts are used to produce 
the percussive action of the machine—one fixed, and the other moving. The 
cylinder and cover may be considered as the fixed part, and the piston and 
rod—which are forged solid—as the moving part; and these are all that are 
required to produce the reciprocating action of the machine. The rotation of 
the tool is obtained by a rifled bar, which is fitted with a ratchet-wheel 
recessed into the caver of the cylinder. There is no automatic action for 
advancing the drill to follow up the work, the reason assigned for its absence 
being that experience has shown that the advantage gained by an automatic 
arrangement was by no means an equivalent for the extra trouble and 
expense they entailed. 
A new rock-drill, which has for some time past been worked successfully 
in the United States, has recently been introduced into this country. It is 
the invention of Mr. Ingersoll, and the main points which constitute its 
novelty are the giving a rotary motion to a piston—either steam- or air- 
moved—and conveying that motion to the drill by means of a spiral rod 
connected to the piston. This rod has an adjustment, so that, when desired, 
the piston may work direct in one direction and be made to rotate in another. 
There is also an arrangement of tappets, by which the piston is forced 
slightly back just before the drill strikes the rock. A cushion is thus formed, 
which prevents the piston striking the end of the cylinder, and the shock of 
impact is received only by the drill-piece, and is not communicated to the 
other parts of the apparatus. The feed-motion of the drill is also governed by 
a tappet, which is struck by the piston in its forward stroke, and as the drill 
progresses into the rock. 
GEOLOGY. 
Physical Geology.—Mr. J. F. Campbell, in a paper on ‘ Polar Glaciation,” 
read before the Geological Society, described his observations made during 
thirty-three years, and especially those of last summer, when he travelled 
from England past the North Cape to Archangel, and thence by land to the 
