PREFACE. Xlll 



Collected Papers, has been translated at his suggestion. It con- 

 tains a full description of the methods by which the difficulties 

 of the investigation were in the first instance overcome, and 

 the reader will find it to be an indispensable introduction to the 

 other two Memoirs on Torpedo, which contain his more recent 

 observations. As each of the three memoirs is complete in itself, 

 and is preceded by a summary of the subjects discussed in each 

 paragraph, no introduction is needed. It may not, however, be 

 out of place to draw attention to the very remarkable discoveries 

 recorded in the concluding paper relating to the fact of ' irre- 

 ciprocal conduction,' which the author has proved to exist in a 

 remarkable degree in the columns of the electrical organs of 

 Torpedo. 



The Editor regrets that the publication of the volume has 

 been unduly delayed, in consequence of the unexpected diffi- 

 culties experienced by the translators in their work. The 

 subject is so new to English scientific literature, that much 

 time is unavoidably lost in deciding between the two alterna- 

 tives, of using Germanised phraseology and of coining English 

 equivalents for the forms of expression used by German writers. 

 In general, the latter alternative has been preferred, but not 

 without a heavy sense of responsibility. Whether successfully 

 or not, great pains have been taken to select such equivalents 

 as appear most accurately to express the meaning of the original, 

 and the translators have, as a rule, consented to employ the same 

 equivalents for the same words. 



