Dr. P. Riess on the Law of Electric Discharge. 525 



vour to ascertain the latter by experiment. But most certainly 

 experiments must be justified by theory, and exactly performed 

 and described if any weight is to be attached to theu]. 



Far more irksome to me than this explanation, is the discus- 

 sion of the other portion of the memoir which consists of the 

 frequently-repeated but unjustified assertion that my own in- 

 vestigations on heat, by which, at the expense of much time and 

 trouble, I have arrived at simple laws, are nothing more than 

 mere reproductions of the author's previous experiments. It 

 is quite true, and has been acknowledged by me, that his un- 

 satisfactory and inconclusive experiments were the cause of my 

 investigations, which were rewarded with a better result. But 

 the credit of having opened up an investigation, although it is 

 by no means small, rarely satisfies those who led the way ; they 

 require more, even though they should only acquire it in the 

 eyes of those who arc unacquainted with the subject. '■ It is 

 a course by no means uncommon in the history of physical 

 science." 



Sir William Harris had made a great many electrical ex- 

 periments, and from them, without possessing the necessary 

 knowledge, had deduced numerous results which always re- 

 mained unintelligible to me, as they were often in contradic- 

 tion to well-known facts, and even with the experiments of the 

 author himself. I was not aware that any one, either here or 

 in England, had found these results more intelligible than I 

 had done. Of course, now that my endeavours of many years 

 have made known the laws of electrical heat, some experiments 

 out of this mass have become more comprehensible, but it is 

 certain that even these experiments, cancelled by other contra- 

 dictory ones, would never have rendered the discovery of these 

 laws possible. Nothing remained for me to do, in the state- 

 ment of my investigations, except to bring the existence of these 

 experiments to the knowledge of the reader, and then, on my 

 own account, to place the subject, which had been confused in 

 the highest degree, in a clear light. My first memoir on electric 

 heat (1837) commences with the mention of Harris's most recent 

 work, a memoir which the author often quotes, and in which he 

 had summed up his previous observations *. As besides elec- 

 trical heat other phfenomena are investigated in this memoir, 

 I gave a complete abstract of it in Dove's Rcpertorium der 

 Physik, Berlin, 1838, and described the instruments and ex- 

 periments mentioned therein as exactly as the statements of the 

 author enabled me to do. All the results of this memoir which 

 I considered as correct I have since made use of under the name 

 of the author with suitable acknowledgments. 



* " On some Elemcutary Lavva of Electricity," Phil. Trans. 1834. 



