388 HERMANN VON HELMHOLTZ 



again, and to enlarge it, and had already begun experiments 

 with other combustible substances. Much of the rest also is 

 incomplete, because the time-limits of the competition obliged 

 him to be content with temporary determinations of certain 

 points, which he could with more time have worked out more 

 carefully and accurately: these cannot now be altered. Nor 

 again am I sufficiently sure of his views in these matters, for 

 he worked quite independently, and seldom asked my advice. 

 It was only when the problem was down on paper that he used 

 to show it to me, and discuss it. I must therefore confine 

 myself to the alteration of any obvious errors on the part of 

 the copyist, and the modification of a few points that are not 

 clearly stated, where I can be certain that the author himself 

 would have altered them in the same way, if he had looked 

 through the proof-sheets/ 



The loss of their son was paralysing to the sorely-tried 

 parents, and Helmholtz, who was quite broken down, went 

 to Switzerland in the middle of August, to recuperate in mind 

 and body amid new impressions. 



' Do not write too much/ he writes from Munich to his wife ; 

 1 try to sleep as much as possible both day and night. Since 

 we both have work to do in the world, and may not yet lie down 

 and give it up, we must take care to remain fit for it. We 

 must not leave Fritz just yet, but the future has become 

 frightfully indifferent to me. I shall continue to do my work, 

 but whether it is for a long or a short while begins to be all 

 one to me now/ 



His letters show that Nature had a beneficial effect upon 

 him in Pontresina : he took long walks, climbed the Piz 

 Languard, which he had shrunk from for four years, and 

 began once more to occupy himself with various and 

 complicated problems. At the end of September he attended 

 the Scientific Congress in Heidelberg, at which Hertz delivered 

 the Address that has become so famous for its lucid simplicity 

 and its profound content. 



1 1 came across the whole Siemens family, and Edison and 

 his wife, the first evening in the Schloss Garden. Mr. Edison 

 is a beardless individual somewhat resembling Napoleon I, 

 but far kindlier, with an almost childlike expression and 

 clever eyes, but he is very hard of hearing. In reply to our 



