| OCR Text |
Show a Phones Gice Warn'r.r: of Fire Damp in n: Hundreds of inw nioi-s ''haw applies their brains to lie matter of lindln-.' ; certain means of detecting tire damp, the cause of such a large proportion of mine disasters. So far no completely com-pletely reliable method has been found; but it is believed that a development devel-opment of the latest idea will solve ; the problem. ' ; This idea consists in the use of a i , pair of telephones of a delicate kind, one of whkh is placed in the upper galleries, where the air is known to be pure, while the other is fixed in the lower workings. Wires from each lead I to a central instrument. I Beside each of the telephones is a I pitch-pipe Into which a current of air Is blown by a fan. The two pipes are i tuned to give exactly the same musical musi-cal note. So long as all Is well only one note Is received and given out by the cen-j cen-j j tral telephone; but directly fire damp f ! occurs the nir supplied by the fun to Z tile pipe In the lower workings be-" be-" : comes changed In quality and this al-iL al-iL ters the note very slightly. That Is, the upper pipe, of course, remains unchanged, and the result Is ..' that instead of a single clear note the central instrument emits a discordant noise which Immediately attracts the attention of the man in charge, warn Ing him that there Is Ore damp in the lower galleries. Philadelphia Inquiivr. |
