The difficulties attending the application of the glow-lamp at the working places through the medium of moveable leads connecting the lamp with the conductor were illustrated not only by the experiment instituted at Earnock Colliery, in the summer of 1881, but also by an earlier attempt, which was witnessed, in the spring of the same year, by Your Commissioners, to apply the glow-lamp to the illumination of working places in Pleasley Colliery, near Mansfield, where Mr. Crompton carried on some interesting experiments, probably the first in this direction, which were, however, not long pursued. .

On that occasion the obvious liability was exemplified of men to trip over or become entangled in the conducting wires which connect the lamps with the main leads and which, lying upon the ground, can be seen only with difficulty. Such an accident might not only lead to the injury of the wire, or to its being torn away from the main conductor, but might also cause the lamp to be brought into violent collision with the ground or other hard object, or to be sharply jerked. In the former case the lamp might be fractured, and this, in the presence of an explosive gas-mixture, might lead to disastrous results, as it has been demonstrated by experiment that if a lamp be broken under such conditions, while the carbon filament is still incandescent, the gas mixture may become ignited, even though the carbon is almost instantaneously burned up when air has access to it. Even if the lamp be not fractured, a fall or violent jerk may cause the carbon filament to break or became detached from its supports, whereby the light would be extinguished.