Improved Fire Damp Detecter.

* IMPROVED FIRE-DAMP DETECTER.

The object of the present paper is to show that with the assistance of the fire-damp detecter, the tin shield, or any other description of lamp, is made as sensitive as the Davy, while its other advantages of resisting velocity, etc., are not in any way interfered with.

He reported the stall to be free from gas, but when the manager and steward visited it with the detecter, which they applied to the roof (where it would have been difficult to put even a small Davy), it drew a sample of the atmosphere which, on being put to the test tube in the tin-shield lamp, at once showed the presence of fire-damp.

Out of twenty-eight tests in a mine working a long-wall face the Davy showed gas only eleven times, while the detecter showed it in every case.

The detecter, as will be perceived from the one exhibited, and the accompanying sectional drawing, consists simply of an oval-shaped India rubber ball, fitted with a mouthpiece.

It will be apparent from the small size and elasticity of the detecter that the test can easily be made with one hand, and when the ball is allowed to expand a vacuum is formed within it, and a sample of the atmosphere drawn from the breaks, cavities, or highest parts of the roof, or, of course, any portion of the mine.

1. The detecter, on account of its size, can be placed in a break in the roof where an ordinary lampeven a small Davycould not be put, and a purer sample of the suspected atmosphere is obtained than would be the case even a few inches below the level of the roof, 2.

The lamp can be kept in a pure atmosphere while the sample is obtained by the detecter, and at a greater height than the flame in a safety-lamp could be properly distinguished.

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.

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.

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.)

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.

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 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.

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.

With the detecter this is avoided, as a large flame can be used, which is considered by some a preferable means of testing for small quantities; and the test can be made without risk.

As regards the use of the detecter with open lights, several of the foregoing advantages or modifications of them will apply.

For the reasons given, I venture to submit that the difficulties and dangers I have mentioned will be largely reduced, if not wholly overcome, by the use of the fire-damp detecter.