Discovery of the Composition of Water. 49 



earnest desire to publish his papers in the Transactions, and 

 to meet his wishes as to the manner of bringing forward his 

 views on the composition of water, — views, it is manifest, 

 which gained importance after the careful experiments had 

 been made, and made known by Mr Cavendish, and after him 

 by Lavoisier and La Place. 



For many years, it is deserving of remark, the honour of 

 the discovery of the composition of water was divided be- 

 tween Mr Watt and Mr Cavendish, — or rather, I should say, 

 given to each undivided, — to Mr Watt for the happy thought 

 or conjectures (" Conjectures on the constituent parts of 

 water") — to Mr Cavendish for the experiments and infer- 

 ences from them in proof of the composition of water.* 



Lord Brougham, in commenting on some remarks made 

 by the Rev. Vernon Harcourt in support of Mr Cavendish as 

 an independent discoverer, not a plagiarist, observes, — " It 

 may be as well to repeat the disclaimer already very dis- 

 tinctly made, of all intention to cast the slightest doubt upon 

 that great man's perfect good faith in the whole affair; I 

 never having supposed that he borrowed from Mr Watt, 

 though M. Arago, Professor Robison, and Sir H. Davy, as 

 well as myself, have always been convinced that Mr Watt 

 had, unknown to him, anticipated his great discovery." t This, 

 probably, will be the decision of posterity ; and, as I have be- 

 fore remarked, it is the one equally honourable to the two 

 distinguished men concerned, whose reputations should be 

 as cherished and dear to us — if gi'atitude is not a mere 

 word, — as their labours have been glorious and above all 

 praise. Is there not a mistake and a meanness in endea- 

 vouring to detract from the one, to add, if that be possible, 

 to the reputation of the other ] 



* What, it may be asked, constitutes a discovery ? Is not Sir John Ilerscbel 

 right in the principle, that " discovery consists in the certain knowledge of a 

 new fact, or a new trutli, a knowledge gruuiidL-J on positive and tangible evi- 

 dence as distinct from bare fuspicion or surmise that such a fact exists, or that 

 such a proposition is true ;'' — and is he not right as to the time of a discovery, 

 that it is when the discoverer is first enabled to say to himself or to a bye- 

 stander, " / am sure that such is the fact ,-' and 1 am sure of it, " for such and such 

 reasons." — Address to the Roy. Astron. ISoc. in Edin. New Phil. Journal, vol. xlvi., 

 p. 256. 



t Historical note by Lord Brougham. Correspondence, p. 256. 

 VOL. XLVII. NO. XCIII. — JULY 1849. D 



