1864. | Mining, Mineralogy, and Metallurgy. 145 
the connecting rod to which the pick is attached, acting as a substitute 
for the piston, in this way the required length of stroke is obtained, as 
it were, within the cylinder itself. 
This machine is very small and compact, being two feet two inches 
high, and three feet long, the pick being two feet six inches in length. 
As in the former case a mah and a boy attend the machine in its pro- 
gress along the ordinary tramway of the colliery. 
The following diagrams will render clear the difference between 
the two machines. Fig. 1 represents the old patent arrangement: a 
is the cylinder, b the piston, c the piston rod, d the connecting rod, e 
the crank or lever. Fig. 2 represents the new patent trunk arrange- 
ment: a is the cylinder, b the piston, ¢ the trunk, d the connecting 
rod, e the crank or lever. 
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Fia. 2. 
Hither of these machines is guaranteed to be capable of under- 
cutting a seam of coal to the depth of three feet, and to the length of 
150 yards, along the face of the coal, in the space of eight hours. These 
machines can be worked either by compressed air or by steam. At 
the Ardsley Pit, air has been employed, and the experience of eighteen 
months confirms its advantage over any other motive power, for this 
purpose. The air is pressed into a receiver on the surface, by an 
ordinary steam-engine, to a pressure of from 45 to 50 lbs. to the inch. 
It is led down the shaft 80 fathoms deep in 44-inch metal pipes, and 
hence in pipes of diminished diameter in the several directions of the 
workings, and finally into the “ Banks”’ or working faces by India- 
rubber tubing of 14-inch diameter. 
The use of air, underground, has many advantages. It is free 
from any kind of danger, and exceedingly manageable ; there is 
nothing of an inconvenient or annoying character to be guarded 
against. It is clean, dry, pure, and cool. 
Beyond all this, when the air has performed its mechanical work, it 
may be made available for sanatory purposes. When discharged from 
the cylinder of the coal-cutting machine, under a pressure of three 
VOL. I. L 
