relative to Black, Watt, and Cavendish. 109 



Your reprinting now these old doubts is the more unac- 

 countable, not only because they consist so ill with your pro- 

 fession of belief in the good faith of Cavendish, and are indeed 

 a mere trifling after that point has been satisfactorily esta- 

 blished, but because I have corrected the particular error out 

 of which this tissue of suspicions was spun ; and you are now 

 apprised that the Secretary of the Royal Society at that time 

 was Mr. Maty, and not, as you persist in taking for granted, 

 Cavendish's friend Dr. Blagden, who did not enter on the 

 office till May 1784. " So that," as I told you in the Appendix 

 to my address to the British Association, "he is not liable to 

 the suspicion intimated by Lord Brougham, of having shown 

 Watt's letter to Cavendish, nor to the reproach which M. 

 Arago casts upon him, of not speaking the whole truth respect- 

 ing the precise date at which Watt's opinions were made 

 known in London." 



The confidence which you place, with so much simplicity, in 

 the innocence of M. Arago's " intentions" contrasts strangely 

 with the disposition you have shown to suspect Cavendish and 

 Blagden : for M. Arago does not, like yourself, "just hint a 

 fault," but retorts in good set terms on the English philoso- 

 phers the imputation which Blagden had cast on Lavoisier, 

 "That he had told the truth, but not the whole truth." "This 

 is a heavy charge," says your illustrious colleague; "let us 

 see whether all w/io took part in this affair are not liable to 

 the same reproach;" — and then in a style of pointed irony, 

 into the spirit of which I should have thought you apt enough 

 to enter, he proceeds to fix the charge on all the parties con- 

 cerned. 1 believe I have given no more than the plain mean- 

 ing of these clever sarcasms when I said, " The Secretary of 

 the Academy has not confined himself to taking from Caven- 

 dish the honour of this discovery, but has in fact imputed to 

 him the claiming a discovery which he borrowed from another; 

 of inducing the Secretary of the Royal Society to aid in the 

 fraud, and even causing the very Printers of the Transactions 

 to antedate the presentation copies of his paper." 



The real truth is, that M. Arago having, when in England, 

 heard but one side of the story, was persuaded of the insin- 

 cerity of Cavendish. If he is now disabused of this persua- 

 sion, I hope he will choose another method of withdrawing 

 what he wrote under such an impression than that which you 

 have framed for him in the following protest. " As a strange 

 notion seems to pervade this paper that every thing depends 

 on the character of Cavendish, it may be as well to repeat the 

 following disclaimer, already very distinctly made, of all in- 

 tention to cast the slightest doubt upon that great man's per- 



