PROFESSOR AT HEIDELBERG 205 



Optics Helmholtz had devoted all his energies to the preparation 

 of his great work on Acoustics, and by the beginning of 1861 

 was feeling that after years of preparation he might soon hope 

 to lay the results of his profound discoveries in acoustics and 

 the art of music before the educated world. Soon after the 

 heavy misfortune that befell Lord Kelvin, Helmholtz wrote on 

 January 16, 1861, to Thomson's wife : 



' I have been working all the winter at my physiological 

 theory of music, and have only two chapters left to write ; 

 then the first draft of it will be ready, though much will doubtless 

 have to be worked up in detail, and improved. I hope to give 

 the book to the printers after Easter. Mr. Thomson will find 

 a great deal that is new since we discussed it last summer, 

 which I have put in while I was working out the details. 

 I have penetrated a long way into the Theory of Music with 

 my physical theories, much farther than I dared to hope at 

 the outset, and the work has amused me considerably. In 

 developing the consequences of any valid general principle 

 in individual cases, one constantly comes on new and quite 

 unexpected surprises. And as the consequences are not 

 arbitrary, and contingent on the caprice of the author, but 

 develop according to their own laws, I often have the im- 

 pression that it is not my own work that I am writing out, but 

 some one else's. Mr. Thomson must have found the same 

 thing in his own work on the mechanical theory of heat. 

 I have also had to look through a great deal of music, and to 

 study the history of music. The Scotch Ballads have been 

 of great use for this, as they have preserved many of the 

 ancient forms.' 



A paper on ' The Theory of Reed Pipes ' (July, 1861) con- 

 cluded the publication of Helmholtz's detailed acoustic obser- 

 vations, and he went on to formulate a physiological acoustic 

 as previously announced to Thomson. 



General happiness, and satisfaction with his new circum- 

 stances, had restored his mental energy and inexhaustible 

 powers of work, and with these he had recovered his old 

 delight in art and nature, and conceived the notion of building 

 the bridge to lead from physics and physiology to aesthetics. 



At the close of the session, after making a cure at Kissingen, 

 he took a long journey in Switzerland and Italy with his young 



