510 Transactions. — Miscellaneous. 



Art. LXXIV. — Analogy between Light and Sound : Are they 



Convertible ? 



By Miss Annette Wilson. 



[Read before the Otago Institute, 11th October, 1892.] 



That a certain analogy exists between light and sound has 

 long been a recognised fact, and more or less commented on. 

 But that that analogy should be so complete as to argue an 

 affinity between them — nay, more, that it might even be 

 possible to convert the one into the other — this is by no means 

 so generally admitted. 



In this idea, which I have long entertained, it would appear 

 that I am not alone, as only a short time ago mention was 

 made in one of the daily papers that Edison purposed making 

 us hear noises in the sun, and this was to be effected by con- 

 verting the rays forming the spectrum into sound. 



It is my purpose to-night to illustrate this idea, first 

 directing your attention to some of the remarkable analogies 

 existing between light and sound, and then translating sound 

 into colour, by what I believe to be a novel process or experi- 

 ment, using for that purpose coloured glasses. 



We know that both light and sound can be converted into 

 heat. We also know that light, sound, and radiant heat are 

 analogous in their laws and conditions. Professor Tyndall 

 remarks upon this in his work upon " Sound." He says, 

 " The action of sound is exactly the same as that of light and 

 radiant heat. They, like sound, are wave-motions ; like sound 

 they diffuse themselves in space, diminishing in intensity 

 according to the same law ; in fact, every experiment on 

 the refraction of light has its analogue in the refraction of 

 sound." 



Does not this alone portray the affinity of light, sound, and 

 radiant heat, and suggest the idea that ultimately they may 

 be found to be but different manifestations of one and the same 

 thing, as we see illustrated by ice, water, and snow ? 



Let us now briefly consider the way in which light and 

 sound are conveyed to our senses, that we may the better trace 

 their analogy. 



Light and sound, as we know, are not substances, but only 

 the vibrations of substances, which vibrations are conveyed to 

 our senses by pulsations through a connecting medium. Light 

 reaches the eye by pulsations through ether, which pervades 

 space ; sound reaches the ear by pulsations through atmo- 

 spheric air. 



