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 217
ther 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… … Fig. 109. the pile. I now explore the spectrum by pushing thethermopile gently along. The slit now lies in the violet—yet there is no heating effect. The blue, the peacock,the green, and the yellow are successively explored—yet the spot of light remains at the zero. These wavesdo not produce…
Light · X-rays
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