WONDERFUL NEW INSTRUMENT.

Digger (Invercargill RSA), Issue 42, 7 January 1921, Page 15

WONDERFUL NEW INSTRUMENT.

An instrument that can detect the presence of a man 200 yards away merely by the heat his body radiates seems almost incredible, but that is oniy because most of our natural senses are so dull compared to the artiftcial senses devised by science, says "Everyday Science." Such an instrument was perfected just before the end of the war, and would probably have been used if the i^hting had lasted another winter. It consists of a thermopile, or very sensitive thermometer, set in the focus of a concave mirror, together with a galvanometer. The heat radiations of any object warmer than the surrounding atmosphere, when focussed by the mirror, act on the thermopile and cause deflections of the galvanometer. In actual tests on cold nights the instrument recorded the heat rays from the body of a man 600 feet away, and a man lying in a shell-hole 400 feet away was detected as soon as he lifted his head above the ground level. No man could cross the range of the instrument without his presence being indicated. The instrument was to have been used for watching No Man's Land on winter nights, and giving warning of raids.