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elastic planes, and throwing them into vibration by means of a violin-bow 

 drawn across the edge ; this was presented to the Royal Society in 1833, 

 and subsequently published in their Transactions, and is probably the 

 most remarkable of his early scientific labours ; for he showed that, in 

 square or rectangular plates, every figure however complicated was the 

 resultant of two or more sets of isochronous parallel vibrations ; and by 

 means of some simple geometrical relations he carried out the principle 

 of the " superposition of small motions " without the aid of any profound 

 mathematical analysis, and succeeded in predicting the curves that given 

 modes of vibration should produce. 



In 1834 Wheatstone was appointed to the chair of Experimental Physics 

 at King's College, London. In fulfilment of the duties of his office he 

 delivered a course of eight lectures on Sound in the early part of the f ol- 

 lowiug year ; but his habitual though unreasonable distrust of his own 

 powers of utterance proved to be an invincible obstacle, and he soon after- 

 wards discontinued his lectures, but retained the professorship for many 

 years. Although any one would be charmed by his able and lucid expo- 

 sition of any scientific fact or principle in private, yet his attempt to 

 repeat the same process in public invariably proved unsatisfactory. An 

 anecdote may here be mentioned in confirmation of this his peculiar idio- 

 syncracy. Wheatstone and the writer of this memoir were for several 

 years members of a small private debating society, comprising several 

 familiar names in science, art, or literature, that met periodically at one 

 another's houses to discuss some extemporized subject, and every member 

 present was expected to speak : Wheatstone could never be induced to 

 open his lips, even on subjects on which he was brimful of information. 

 Several of his more important investigations were for the same reasons 

 from time to time brought before the public by Faraday in the theatre 

 of the Royal Institution. 



In 1835 Wheatstone communicated to the British Association a paper 

 " On the Attempts which have been made to imitate Human Speech by 

 Mechanical Means ; " and he produced a much improved edition of De 

 Kempelen's speaking-machine ; but his researches in this direction were 

 not long continued, and have since been far surpassed by others. 



The analogies of vibratory motion led the philosophic mind of Wheat- 

 stone from the subject of sound to that of light. In 1838 he communi- 

 cated to the Royal Society an account of some remarkable and hitherto 

 unobserved phenomena of binocular vision, with a description of the 

 reflecting stereoscope, an instrument by which these phenomena were 

 first illustrated. The conception that the idea of solidity is derived from 

 the mental combination of two pictures of the same object in dissimilar 

 perspective, as seen by the two eyes respectively, is undoubtedly and solely 

 due to Wheatstone. In demonstration of this principle he drew two 

 outlines of the same geometrical figure or other object, just as they would 

 be seen in perspective by either eye respectively ; and these outlines were 



