1870.] Light and Sound. 13 



partially destroys the sound-shadow which such a pillar would other- 

 wise throw. Iu former time it was urged that if light be a wave- 

 motion, there ought also to be inflection and only partial shade behind 

 an opaque object. The inflection of light has since been discovered ; 

 light does slightly encroach, in the form of fringes, upon the shadow 

 cast by an object. Nevertheless, owing to the rectilinear propaga- 

 tion of hght, shadow is a characteristic feature of light. Is there 

 an analogous sound-shadow ? There is, notwithstanding inflection. 

 If we pass close beside a church, the bells of which are ringing, we 

 shall notice that on coming beneath the tower we enter a region, 

 nearer the source of sound, yet where the sound is very perceptibly 

 less audible; and as we gradually emerge from this acoustic shadow 

 the sound grows louder. So also when listening to an approaching 

 train, as it is occasionally hidden from view, accompanying sound- 

 shadows flit across the ear. And in a more elastic medium than 

 air, such as w&ter, sound-shadows would, necessarily, be more 

 intense and sharply defined. 



§ 9. Harmony of Colour and Music. 



It is in this division of our subject that we find a wide-spread 

 and tacit acceptance of the analogy of light and sound. We instinc- 

 tively criticize in like terms the works of a painter and a musician. 

 We speak of the harmonious blending of colours in a picture, as we 

 do of the chords in a musical composition. We compare, apparently 

 without reason, the order of colours in a rainbow to the notes of the 

 gamut. Like Locke's blind man who said scarlet was to him as 

 the deep sound of a trumpet, we think of red as a low note, of blue 

 as a high one. We find, as a rule, that good taste in art goes hand- 

 in-hand with good taste in music ; hence a large number of eminent 

 painters have been excellent musicians* All this points to the 

 fact that pleasure given to the eye or ear evokes similar mental 

 impressions, 



Now the question arises, Has all this aesthetic oneness of colour 

 and music any physical foundation, over and above that general 

 analogy we have so far traced between light and soUnd ? We believe 

 the following considerations will show not only that it has some 

 foundation, but that the analogy is far more wonderful than has 

 hitherto been suspected. 



Let us take as our standard of colours the series given by the 

 disintegration of white light, the so-called spectrum. As our stand- 

 ard of musical notes let us take the natural or diatonic scale. We 

 may justly compare the two : for the former embraces all possible 

 gradations of simple colours, and the latter a similar gradation of 

 notes of varying pitch. 



* Omitting many living painters, of whom this is true, it is sufficient to name 

 Tintorretto, Caracci, Salvator Eosa, Dominichino, Guido Eeni, Leonardo da Vinci ; 

 and Rubens also is said to have been passionately fond of music. 



