by the detecter, and at a greater height than the flame in a safety-lamp
could be properly distinguished. The test can afterward be made in a safe
place, at some distance from the explosive atmosphere; and, owing to the
vacuum formed, the ball (without closing the mouthpiece) has been carried a
mile or more without the gas escaping. 4. The detecter supplies a better
knowledge of the condition of the working places, especially in breaks and
cavities in the roof; which latter, with the help of a nozzle and staff,
may be reached to a height of ten feet or more, by the detecter being
pressed against the roof and sides, or by the use of a special form of
detecter. 5. Being able at will to force the contents of the detecter on to
the flame, the effects of an explosion inside the lamp need not be feared.
(This danger being removed, admits, I think, of the glass cylinder being
made of a larger diameter, whereby a better light is obtained; it may also
be considered quite as strong, when used with the detecter, as a lamp with
a small diameter, when the latter is placed in an explosive atmosphere.) 6.
The use of the detecter will permit the further protection of the present
tin shield lamp, by an extra thickness of gauze, if such addition is found
advantageous in resisting an increased velocity. 7. In the Mueseler,
Stephenson, and other lamps, where the flame is surrounded by glass, there
is no means of using the wire for shot firing. The detecter tube, although
protected by two thicknesses of gauze, admits of this being done by the use
of a special form of valve turned by the mouthpiece of the detecter. The
system of firing shots or using open lamps in the same pit where safety
lamps are used is exceedingly objectionable; still, under certain
conditions shots may be fired without danger. Whether safety lamps or
candles are used, it is thought the use of the detecter will afford such a
ready means of testing that more examinations will be made before firing a
shot, thereby insuring greater safety. 8. In testing for gas with a safety
lamp there is a fear of the light being extinguished, when the lamp is
suddenly placed in a quantity of gas, or in endeavoring to get a very