Wilson. — Analogy between Light and Sound. 513 



required to produce the seven colours, and if we take the pro- 

 portion of increase in the number of vibrations in a second 

 required to produce the seven musical sounds of a diatonic 

 scale, we shall find these proportions exactly the same. Some 

 years ago, in England, I attended a lecture entitled " The 

 Correlation of Light and Sound," and the lecturer produced 

 on a screen a table of the ratio of wave-lengths in a second, 

 producing the seven colours in spectrum, and the seven notes 

 of a scale (of course, wave-lengths vary in number in inverse 

 ratio to their velocity). I exhibit the table which I copied at 

 the time. 



You will here see the names of the seven colours in the 

 spectrum placed over their relations, the seven notes of a 

 scale, with the ratio of their wave-lengths, thus : — Note C, 

 100 = red ; D, 89 = orange ; E, 80 = yellow ; F, 75 = green ; 

 G, 67 — blue ; A, 60 = violet ; B, 53 = ultra-violet. Any dia- 

 tonic scale would yield the same proportion of wave-lengths. 

 Of course, the division in both is arbitrary, both sound and 

 light being continuous from their lowest to their highest 

 manifestations. 



If we take the primary colours — red, yellow, and blue — in 

 the above table we shall find that they occupy the same posi- 

 tion in the spectrum as do the three notes forming the com- 

 mon chord in the scale — viz., the first, third, and fifth. More- 

 over, any two notes that sound discordant stand under colours 

 that will not harmonize to the eye, and ditto vice versa. 



By the following illustrations on the screen I hope to make 

 you realise the capability of colour to impress the brain in the 

 same way as sound does the ear. I am aware that it is a 

 very crude and inadequate attempt, but the means at my 

 command are limited. In my mind's eye I can see a sym- 

 phony of Beethoven rendered by electric flashes of coloured 

 light, with all its grand concords and discords, producing the 

 various emotions of peace or agitation, joy or sorrow, triumph 

 or despair. We must remember that music began by simple 

 melodies only, just as to-night I can give you such Only in 

 colour. What might not be done in the future? 



Slide 1a : Colours in spectrum — red, orange, yellow, green, 

 blue, violet, ultra-violet. 



Small frames : Discord and concord. 



Slide 1b : Four opening bars of Beethoven's Symphony in 

 C minor, opening in E flat major. First four notes all pri- 

 33 



