Light visible and invisible : a series of lectures delivered at the Royal Institution of Great Britain, at Christmas, 1896 (1897)
Thompson, Silvanus Phillips, 1851-1916, Royal Institution of Great Britain · New York : Macmillan · leaf 216
ermometer—the thermopile. If you want toknow all about this instrument, you must refer totreatises on electricity. All I need say now about it isthat it is an apparatus, Fig. 109, which is exceedinglysensitive to heat, and which, when the face of it iswarmed, generates an electric current. The… … whether the face of the thermopile is warmer or colder 196 LIGHT LECT. than the air of the room. If it is warmer the spotwill move to the right; if colder, to the left. The spectrum now falls upon a small brass screenwith a slit in it, behind which is the thermopile ; and atpresent the part of the…
Light · X-rays
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