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Firstly then you notice, when a fragment of sodium is placed in a platinum spoon and introduced into a Bunsen's flame, an intensely yellow light is produced. It corresponds in refrangibility with the yellow band of the spectrum. Like our tuning-fork, it emits waves of a special period.

Newall's telescope were downright clumsiness, had striven to devise a seeing apparatus, capable of exact self-adjustment to all degrees of light, all gradations of distance, all varieties of refrangibility, it could not have adopted a contrivance more exquisitely ingenious, or evincing more minutely accurate knowledge of the most secret laws of optics, than the mechanism of the eye apparently betokens, let it still be admitted to be not quite beyond the bounds of possibility, that not skill but the blindest and densest ignorance may have presided over the whole operation.

In his Philosophy of the Inductive Sciences he continually asserts, that propositions which not only are not self-evident, but which we know to have been discovered gradually, and by great efforts of genius and patience, have, when once established, appeared so self-evident that, but for historical proof, it would have been impossible to conceive that they had not been recognised from the first by all persons in a sound state of their faculties. “We now despise those who, in the Copernican controversy, could not conceive the apparent motion of the sun on the heliocentric hypothesis; or those who, in opposition to Galileo, thought that a uniform force might be that which generated a velocity proportional to the space; or those who held there was something absurd in Newton’s doctrine of the different refrangibility of differently coloured rays; or those who imagined that when elements combine, their sensible qualities must be manifest in the compound; or those who were reluctant to give up the distinction of vegetables into herbs, shrubs, and trees.

Thus again the discovery of the polarisation of light led to experiments which ended in the discovery of the polarisation of heat a discovery that could never have been made without the antecedent one. Thus, too, the known refrangibility of light and heat lately produced the inquiry whether sound also is not refrangible; which on trial it turns out to be.

The Academy pronounced its judgment gravely, without inflicting a word of ridicule; for example, it did not speak of harlequin; but it did not therefore remain the less established that the pretended experiments, intended, it was said, to upset Newton's, on the unequal refrangibility of variously coloured rays, and the explanation of the rainbow, &c., had absolutely no scientific value.

Now, as has been said before, the dissimilar rays having an unequal degree of refrangibility, it will be impossible to obtain a focus by the light passing through a double-convex lens without its being fringed with color. Its effect will be readily understood by reference to the accompanying cut.

To him the world is indebted for the binomial theorem, discovered at the age of twenty-two; for the invention of fluxions; for the demonstration of the law of gravitation; and for the discovery of the different refrangibility of rays of light.

This last effect is attributable to the refrangibility of light, that is, to some of the colors being more refracted than others. He likewise knows that more than a hundred years ago Mr.

In his optical researches, Optiska Undersökningar, presented to the Stockholm Academy in 1853, he not only pointed out that the electric spark yields two superposed spectra, one from the metal of the electrode and the other from the gas in which it passes, but deduced from Euler's theory of resonance that an incandescent gas emits luminous rays of the same refrangibility as those which it can absorb.