xxxix 



cannot tell — I do not know ; but, on the other hand, it is encouraging to 

 think that these are they which, if pursued industriously, experimentally, 

 and thoughtfully, will lead to new discoveries. Such a subject, for instance, 

 occurs in the currents produced by dynamic induction, which you say it 

 will be admitted do not require for their production intervening ponderable 

 atoms. For my own part, I more than half incline to think they do re- 

 quire these intervening particles. But on this question, as on many others, 

 I have not yet made up my mind." 



On the 1st of January the following year, Dr. Hare sent a reply. In 

 Faraday's answer to this, he says : — " You must excuse me, however, for 

 several reasons, from answering it at any length. The first is my distaste 

 for controversy, which is so great that I would on no account our corre- 

 spondence should acquire that character. I have often seen it do great 

 harm, and yet remember few cases in natural knowledge where it has helped 

 much either to pull down error or advance truth. ' Criticism, on the other 

 hand, is of much value ; and when criticism such as yours has done its 

 duty, then it is for other minds than those either of the author or critic to 

 decide upon and acknowledge the right." 



This year he reported to the Trinity House on the necessity and method 

 of examining lighthouse dioptric arrangements, and he had to examine the 

 apparatus intended for Gibraltar. Between Purfleet and Blackwall he 

 made a long comparison between English and French reflecting lamps and 

 between English and French refracting prisms. 



To Professor Auguste Be la Rive, the son of his early friend, he wrote : — 

 " Though a miserable correspondent I take up my pen to write to you, the 

 moving feeling being a desire to congratulate you on your discernment, 

 perseverance, faithfulness, and success in the cause of Chemical Excitement 

 of the current in the Voltaic Battery. You will think it is rather late 

 to do so ; but not under the circumstances. For a long time I had not 

 made up my mind ; then the facts of definite electrochemical action made 

 me take part with the supporters of the chemical theory, and since then 

 Marianini's paper with reference to myself has made me read and experi- 

 ment more generally on the point in question. In the reading, I was 

 struck to see how soon, clearly, and constantly you had and have sup- 

 ported that theory, and think your proofs and reasons most excellent and 

 convincing. The constancy of Marianini and of many others on the opposite 

 side made me, however, think it not unnecessary to accumulate and record 

 evidence of the truth, and I have therefore written two papers, which I 

 shall send you when printed, in which I enter under your banners as re- 

 gards the origin of electricity or of the current in the pile. My object 

 in experimenting was, as I am sure yours has always been, not so much to 

 support a given theory as to learn the natural truth ; and having gone to 

 the question unbiassed by any prejudices, I cannot imagine how any one 

 whose mind is not preoccupied by a theory, or a strong bearing to a theory, 

 can take part with that of contact against that of chemical action. How- 



