Page:Scientific Memoirs, Vol. 1 (1837).djvu/127

Rh colours to the other through the intermediate tints, the first feeling will be changed into an agreeable sensation. Our scale, I repeat it, produces the same agreeable impression upon all, and it is to the inimitable beauty of its colours, and the manner in which they melt into each other, that this effect is due.

According to the law of imaginary colours red harmonizes well with green. In our scale the lakes, which are the finest reds in nature, are between the green tints and the orange, and combine agreeably with both. According to the same law the violet should agree only with the yellow; in the scale the violet tints are between the azures and the ochres, where they produce a very fine effect. The same law is opposed to the combination of yellow and azure, but the scale proves that these two tints combine agreeably, provided they have a certain tone and a certain degree of brightness. It is unnecessary, I believe, to multiply instances. The beauty of the tints and the graduation of the transitions constitute together one of the first secrets of art revealed by the effect of the chromatic scale. But it is not always allowed us to resort to the graduation of the transitions, and the artist requires another guide to show him what he is to do in all circumstances. It cannot be doubted that as there are combinations of sounds more perfect to the ear than others, such as the octave, the fifth and the third, there are likewise concords of colours more pleasing to the eye than others. But these concords should be determined. The field of inquiry is still new; it is possible however that the pursuit may be attended with most success by having recourse to the chromatic scale, which presents the tints in their greatest purity, and so arranged as to form the gamut of colours. This circumstance is an additional recommendation of the scale to the attention of philosophers as well as of artists.

In physics it is usual to speak only of the brightness of colours. But besides being more or less bright, they are more or less intense or deep, beautiful, cheerful, &c. These epithets have been long in common use and are constantly on the lips of painters. In my opinion it is time that they should be admitted into science, and reduced to a more determinate signification than they have in ordinary language.

All who observe the seven colours of the spectrum will instantly perceive that they differ greatly in brightness. The clearest of them is the yellow. Fraunhofer, who has analysed the spectrum with so much care, assigns to that colour the highest degree of brightness.

The tints of our scale as well as the natural colours are far from being