Crick . . . Crack

At 15, John A. Spencer of Revere, Mass., was a mill-hand in a Maine lumber camp. He worked with the night shift and part of his job was to keep the boiler simmering. The boiler had a rounded clean-out door; and when John heaped up a hot fire, this door would go Crick! outward, convex like a bubble. When the fire cooled down, Crack! would go the boiler door, back inward, concave like a saucer.

John Spencer grew to years of discretion and mechanical knowledge. Re- cently, the U. S. Patent Office issued to him a basic patent for a new type of quick-acting thermostatic bimetal device.* Last week, the Westinghouse Electric and Manufacturing Co. obligated itself to him (according to report) to the extent of a million dollars for this patent. The Spencer Thermostat will now appear on a variety of electrical apparatus, chiefly irons, coffee-percolators, water-heaters.

Within the Spencer Thermostat, there will be a little disc of flexible metal. When an iron or percolator gets too hot, crick! will go the disc, convex like a bubble, and cut off the current. When the iron cools, crack! concave like a saucer, and the current will go on again. Two metals in the disc contract and expand with the temperature, but unequally, causing the disc to warp, crick . . . crack!

*There have been previous devices of this type. Most of them broke an electric circuit slowly; an arc formed, injured the con- tact points, in time incapacitated the device.