The London, Edinburgh and Dublin philosophical magazine and journal of science . ours, be able to impress uponthe aether a motion equivalent to the sum of the motions of several atomseach oscillating at one rate ? It is perhaps worthy of remark, that there appears to be a definite rateof vibration for all solid bodies having the same temperature, at which thevis viva of their atoms is a maximum. If, instead of the electric light, weexamine the lime-light, or a platinum wire raised to incandescence by anelectric current, we find the apex of the curve of distribution (B, fig. 3)corresponding thr
The London, Edinburgh and Dublin philosophical magazine and journal of science . ours, be able to impress uponthe aether a motion equivalent to the sum of the motions of several atomseach oscillating at one rate ? It is perhaps worthy of remark, that there appears to be a definite rateof vibration for all solid bodies having the same temperature, at which thevis viva of their atoms is a maximum. If, instead of the electric light, weexamine the lime-light, or a platinum wire raised to incandescence by anelectric current, we find the apex of the curve of distribution (B, fig. 3)corresponding throughout to very nearly, if not exactly, the same refran-gibility. There seems, therefore, to exist one special rate at which theatoms of heated solids oscillate with greater energy than at any other rate—a non-visual period, which lies about as far from the extreme red of thespectrum on the invisible side as the commencement of the green on thevisible one. 2D2 392 Prof. Tyndall on Calorescence. tribution of heat closely resembling that observed in the solarspectrum. &fe. The curve representing the distribution of heat in the electricspectrum falls most steeply on that side of the maximum which Prof. Tyndall on Calorescence. 393 is most distant from the red. On both sides, however, we havea continuous falling off. I have had numerous experiments madeto ascertain whether there is any interruption of continuity inthe calorific spectrum; but all the measurements hitherto executedwith artificial sources reveal a gradual and continuous augmenta-tion of heat from the point where it first becomes sensible upto the maximum. Sir John Herschel has shown that this is notthe case with the radiation from the sun when analyzed by aflint-glass prism. Permitting the solar spectrum to fall upon asheet of blackened paper, over which had been spread a wash ofalcohol, this eminent philosopher determined by its drying-powerthe heating-power of the spectrum. He found that the wet sur-face dried in
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