HELMHOLTZ IN KONIGSBERG 



at their extremities if the eye is directed to an object 

 close at hand, a result that can only be explained by 

 supposing that the lens becomes, in the latter case, 

 more convex. This experiment, difficult of execution, 

 excited the admiration of Helmholtz, who always 

 regarded Young as a man before his time, and one of 

 the greatest of English philosophers. Max Langen- 

 beck, 1 about 1849, came near the true explanation, 

 but it was reserved for Cramer to complete the dis- 

 covery. He observed the image of a flame, reflected 

 from the anterior surface of the lens, by means of a 

 short focus telescope, and noticed the essential fact 

 that the image became smaller when the eye was 

 directed to a near object. 



Helmholtz, unacquainted at the time with the 

 work of Langenbeck and Cramer, now took up the 

 question, and, with his usual thoroughness, went to 

 the bottom of it. He arrived at the same conclusions 

 as Cramer, but he went much farther. Here, again, 

 there was no question of priority. When Cramer's 

 work was brought under his notice by the writings 

 of his friend Donders, who rescued Cramer from 

 oblivion, 2 Helmholtz at once recognised his merits. 

 Donders, in the speech already referred to, said : 

 'If it be a satisfaction to me to venture to claim 

 the first for my countryman, D. A. Cramer, I must 



1 Kl'mische Beitrage. Gbttingen, 1849. 



2 Tijdschrift der Maatschappy -voor Geneeskunde, 1851, vol. xi., p. 15 ; 

 also Nederlandtch Lancet, 2 i. p. 529, 1851-2. 



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