A NEW FIRE-DETECTOR.

A NEW FIRE-DETECTOR.

的希望会见通用识别British inventor has put out a new style of firedetector. The device, it is said, consists of a tube, with very thin walls. It is filled with mercury, at one end of which is a very fine capillary tube connecting with a compensating chamber, and at the other end a platinum wire fused into a normally-empty contact-tube, into which are fused two platinum wires. Under normal conditions the expansion due to heat causes the mercury to flow through the capillary tube into the compensating chamber, for the reason that mercury does not readily flow into the normally-empty contact-tube. If abnormal heat causes such rapid expansion that the mercury cannot pass through the capillary tube, it is forced up into the contact-tube, comes in contact with the two platinum wires, and gives the alarm. The contact-tube and wires being imbedded in plaster of Paris, an increase in the diameter of the capillary tube may be so regulated as to provide free passage for the extraordinary expansion of the mercurv under normal conditions in a bakehouse or foundry, for instance; but any unusual heat will force the mercury into the empty contact-tube, and so give the alarm. In a room 45 ft. square and 45 ft. in height the lighting of a newspaper caused the alarm to be given in fifteen seconds, and in a room measuring 150 by 70 by 80 ft., and supplied by three fire-detectors, a similar cause rang the alarm in twenty seconds.

的希望会见通用识别British inventor has put out a new style of firedetector. The device, it is said, consists of a tube, with very thin walls. It is filled with mercury, at one end of which is a very fine capillary tube connecting with a compensating chamber, and at the other end a platinum wire fused into a normally-empty contact-tube, into which are fused two platinum wires. Under normal conditions the expansion due to heat causes the mercury to flow through the capillary tube into the compensating chamber, for the reason that mercury does not readily flow into the normally-empty contact-tube. If abnormal heat causes such rapid expansion that the mercury cannot pass through the capillary tube, it is forced up into the contact-tube, comes in contact with the two platinum wires, and gives the alarm. The contact-tube and wires being imbedded in plaster of Paris, an increase in the diameter of the capillary tube may be so regulated as to provide free passage for the extraordinary expansion of the mercurv under normal conditions in a bakehouse or foundry, for instance; but any unusual heat will force the mercury into the empty contact-tube, and so give the alarm. In a room 45 ft. square and 45 ft. in height the lighting of a newspaper caused the alarm to be given in fifteen seconds, and in a room measuring 150 by 70 by 80 ft., and supplied by three fire-detectors, a similar cause rang the alarm in twenty seconds.