Studies in spectrum analysis / by J. Norman Lockyer.

  • Norman Lockyer
Date:
1904
Catalogue details

Licence: In copyright

Credit: Studies in spectrum analysis / by J. Norman Lockyer. Source: Wellcome Collection.

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    one light source—the sun. How is it then that with the first class of receiver—the eye—we are enabled, unless indeed we be colour blind, to see all the beautiful and glorious varieties of nature in its ten thousandfold hues ; while the other receiver, the photographic plate, gives us but black and white} Why are roses red, and why are leaves green } There is the same light in the sky, and the same absence of form—the same absence of visibi- lity—in the dark ; yet with the light coming from one and the same light-source we get all these different effects. How is this} It drives us to the conclusion, either that the receivers, to which our attention has been particularly directed, deal with light in very different ways, or that by some means or other they manage to get hold of different kinds of light. Here then we must seek for some explanation of the various colours that we see in nature. We have referred to the receivers, including those, that reflect the light which they receive ; now let us consider the things which send out the light. Among these are the sun, the moon, the stars, gas, and candles which are most familiar to us as sending out light. And it will be well to remark here, and the reason why will be clear by-and-by, that the light which all these senders give to us is white light in the main. But we get other kinds of light. We have, for instance, that of the electric lamp—a very powerful source of light, only a very little less powerful (as some people think) than the sun itself. It proceeds from two carbon poles which are rendered intensely incandescent by means of an electric current.
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