1864. | Mining, Mineralogy, and Metallurgy. 143 
Engine is mounted within this framework: it is actuated by com- 
pressed air, and so arranged as to give the blow of the pick or cutter, 
either by the pull or the push of the piston. Almost any form of engine 
is applicable, but that which is employed with advantage in practice at 
Ardsley Colliery, is the oscillating cylinder principle, whereby is 
obtained compactness of form and diminished friction in the working 
parts. The whole is carried upon wheels with flanges, sometimes 
single and sometimes double, as may be required by the nature of the 
work. It is propelled backward and forward by a wheel and screw, 
or a ratchet and pawl, which is fized on one side. On the other side 
is the valve-lever to regulate the admission and the emission of the 
‘air, and the stroke of the piston when the Machine is at work; 
the man in charge of it moves the ratchet-lever, which is con- 
nected with the gearing of the under-carriage, and thus pushes up 
the carriage on the tram, a distance equal to the cut of the previous 
blow ; and so moves on to the end of the “ bank,” or working face of the 
coal. In seams of three feet, or upwards in thickness, the man may 
sit on a movable seat fixed at the end of the Machine, but in thin 
seams this cannot be done, and he has to kneel on a truck running 
on low pulleys or rollers which travel in the rear of the cutting- 
machine. 
The cut, or groove of the coal, made by hand-labour, is a triangular 
opening varying in size according to the hardness and nature of the 
coal, but averaging from 9 to 12 inches. In firm coal the machine 
makes a cut which is not usually more’than 24 inches’ opening, and 
the under-cut is taken 3 feet into the coal. The Ardsley Coal Com- 
pany state that the coal is obtained in a better condition by machine, 
than by hand cutting, so much so that about 1s. a ton more can be 
obtained for the coal, on the yield of the seam. 
A matter of more importance than this is urged by the proprietors, 
viz. the diminished risk to the persons and lives of the employed. 
Numerous lives are lost by falls of coal. Ié will be well under- 
stood, that, if the miner has made an opening in the lower part of the 
coal, which shall be 12 inches wide on the face, and the superincum- 
bent mass of coal should by its weight fall, much care will be required 
on the part of the workman to keep himself harmless. Often, when 
working in a constrained position, the coalhewer, unable to relieve 
himself from the falling masses, is crushed to death. 
By the machine work there is much less lability to this kind of 
accident. The groove being narrow can be spragged with ease and 
system, and a slip in the coal only closes up the groove. In ordinary 
cases the coal is not pushed out; but, if it does come forward, there 
is little danger to the workman, because he can readily get out of the 
way, and if it catches the machine but litile injury is done. There 
are some technical advantages, beyond those named, which need not 
be noticed in this Journal. 
The length of the coal-cutting machine which we have described, 
has been thought by some to be a disadvantage. Difficulties are said 
to have arisen when it was required to be taken round the short elbows, 
and the abrupt curves, which often occur in a colliery. To obviate this 
