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Cuar. VI, § 2.] HEAT.—CAVENDISH. 929 
(594.) - The Honourable Henry Cavendish, son of Lord qualified to form one, and the writer of it was 
His per- (Charles and Lady Anne Cavendish, was born at Nice, usually fastidious in his judgments of others :—* It 
se his October 10, 1731.1 He entered St Peter’s College, may be said of Mr Cavendish, what can perhaps hardly 
Cambridge, 24th November 1749, where he resided be said of any other person, that whatever he has 
during the usual terms for above three years, when done has been perfect at the moment of its produc- 
he ought naturally to have graduated, which, how- tion. His processes were all of a finished nature. 
ever, he never did. That he had pursued at least Executed by the hand of a master, they required no 
his mathematical studies with ability and success is, correction; and though many of them were per- 
however, nearly certain from the firm hold which he formed in the very infancy of chemical philosophy, 
ever after retained of them. He joined the Royal yet their accuracy and their beauty have remained 
Society of London in 1760, and published his first amidst the progress of discovery, and their merits have 
paper in their Transactions in 1766. From the time been illustrated by discussion, and exalted by time.” 
of his leaving Cambridge for some years his personal After this eulogium of so competent a judge, I 596.) 
history is not known, though he probably resided in shall be satisfied by a simple enumeration of those Chemical 
London. chemical discoveries which were the most splendid pry stect 
(595.) The subsequent history of Cavendish is the history results of his career, but which hardly come within gish, 
His won~ of his studies and his discoveries. ‘The latter were the immediate scope of this dissertation. To him we 
oe published in concise memoirs, written with scrupulous are mainly or entirely indebted for the knowledge of 
aaintite precision, and all printed in the Philosophical Trans- hydrogen as a distinct elastic fluid or gas; of the 
knowledge. actions. If collected (which they have not been) they exact constitution of the atmosphere, and the won- 
these powerful temptations could withdraw him even 
for an hour from the course of study which he had 
marked out; and which constituted for him at once 
labour and relaxation, the end of living, and almost 
life itself. 
would fill but an insignificant volume, yet include all 
the requisites to establish a first-rate reputation. His 
studies no doubt were enormous, for they occupied 
every disposable moment of a life prolonged almost 
to fourscore. They may be guessed at (in addition 
to the published results) from his manuscript remains, 
a few of which have been edited recently, but the 
larger part remains in manuscript in the possession of 
his heirs. Few if any branches of exact science were 
unfamiliar to him ; and his published papers include 
astronomy, mechanics, electricity, heat, chemistry, 
and meteorology, besides which he cultivated mathe- 
matics and geology. His reputation is one of those 
which may be called ina peculiar sense European or 
universal, because it marked a great epoch in science 
to which the publication of his writings materially 
contributed. That epoch was when ‘chemistry be- 
came a science of weight and measure. Cavendish 
was a weigher and measurer almost by nature, and 
entirely so by habit. It appears from his note-books 
that he took the most scrupulous pains to ascertain 
and record the quantities of the ingredients employed 
in every experiment, even though they might be im- 
material to the result; and his whole life was metho- 
his day; and his good opinion was considered by con- 
temporary philosophers as their highest praise. Sir 
Humphry Davy’s opinion of- him’ (recovered and 
published by Dr Davy from a manuscript lecture) 
represents that of such of his countrymen as were 
derful constancy of its ingredients; of the composi- 
tion of nitric acid; and finally, according to the 
opinion of most persons (at least till lately), of 
the non-elementary nature of water, and of its 
precise constituents. This last and crowning dis- 
covery has indeed been contested, and made the sub- 
ject of a prolonged and bitter scientific controversy, 
which hardly could be said to exist until the con- 
temporary generation who witnessed the facts, and 
also the succeeding one, had passed away. For Caven- 
‘dish received until his death, and for nearly thirty 
years after, the unquestioned tribute of at least. the 
primary merit in so great a step in science. The 
topics more peculiar to the present essay (sufficiently 
extensive besides) enable us to dispense with the un- 
welcome task of once more analyzing a controversy 
purely personal, and which has almost filled volumes. 
I shall content myself with stating two considera- 
tions, which must have great weight in turning the 
balance of the evidence (supposing it balanced) in 
Cavendish’s favour. The first is founded on the 
behaviour of Watt himself; the second on the known 
character of Cavendish. 
As to the former consideration, I would remark that 
(597.) 
Watt withdrew the letter to Priestley which he had Contro- 
submitted to the Royal Society and which contained versy on 
his views respecting the composition of water, before Soenbed , 
it had been read at the meetings of that body.? The position of 
causes of this suppression are candidly stated by water. 
Watt in a letter to Sir Joseph Banks, published by 
Mr Muirhead,’ in which he states that he “ thought 
dical in the same proportion. The immense impor- 
tance of Cavendish’s labours to the progress of science 
in his day is found in the unanimous testimony of 
his contemporaries ; and notwithstanding the extreme 
retirement in which he lived, and the rarity of his 
appearances as an author, he was generally regarded 
as perhaps the leading man of science in England of 
1 Life of Cavendish, by Dr George Wilson ; a valuable biography, which has been printed in the series of publications of the 
« Cavendish Society,’ and thus unfortunately has had but a limited circulation, 
> Correspondence on the Composition of Water, p. 30. ~ 
VOL, I. 
* Ibid. p. 62. 
6B 
