280 Notices of Books, [April, 
cording to its rate or the peculiarity of its movements. Lucretius, 
as M. A. Ditte recently observed,* “a exposee la theorie atomique 
avec line vivacite, un eclat, une eloquence qui font du poeme de 
la nature un des chefs-d’oeuvre de la litterature latine ; ” and Dr. 
Smith considers that this philosopher was the only full expositor 
of the dodtrine among the ancients. Newton’s well-known 
words are quoted, as they form an era in the theory of atoms, 
not so much by new ideas as by distinctness, and because 
they eliminate much confusion. Newton held that the primi- 
tive particles of which matter is composed are incomparably 
hard and incapable of wear, for otherwise water and earth 
composed of old worn particles would not be of the same nature 
and texture now with water and earth composed of entire parti- 
cles in the beginning, and therefore, that nature may be lasting, 
the changes of corporeal things are to be placed only in the 
various separations and new associations and motions of these 
permanent particles. The first distindt attempts to define pre- 
cisely the motion of gaseous molecules, and not of atoms, are 
by D. Bernoulli, who says — “ The chief peculiarities of fluids are 
these: ist, they are heavy ; 2nd, they expand in all directions 
unless they are confined ; and 3rd, they allow themselves to be 
compressed more and more, according to the increased force 
employed.” Speaking of a vessel of air with a weighted cover, 
he says — “ So the minute bodies, whilst they impinge on the 
cover, keep it up by their continually-repeated strokes, &c.” The 
views of Davy, Rumford, and Herapath are then given, and it is 
pointed out that Joule investigated experimentally the hypothesis 
that gases consist of small bodies continually impinging on one 
another, their elasticity increasing with the temperature, the 
pressure of the gas being due to the impadt of the particles 
against any surface presented to them. Dr. Smith shows that it 
was the objedt of Graham’s life to find out what the motion of 
the atom was, and claims him to be “ as stridt an atomist as 
perhaps can be found,” and it is certain that he did believe in 
the existence of atoms, but few minds have been more free from 
unconscious bias : we are convinced that he would have aban- 
doned the atomic theory without reludtance if he had found a 
better to replace it. 
We may quote, as it will be familiar to most readers, a para- 
graph just written by Mr. Gladstone, f which will aid us in 
explaining Mr, Graham’s mental attitude. The learned writer 
points out that “ even in the days of Bacon, even in the days of 
Dante, when knowledge, as the word was commonly understood, 
was so limited that some eledt minds of uncommon capacity and 
* “ Constitution de la Matiere,” par M. Alfred Ditte. Ann. Chim. et 
Phys., Feb., 1877, p. 151. 
f On the Influence of Authority in Matters of Opinion. By the Rt. Hon. 
W. E. Gladstone, M.P, 
