THE HAMILTON ASSOCIATION. 39. 
obtained, held it a most wonderful thing and a conclusive proof of 
the ‘truth ” of the hypothesis and of the “ real existence ” of mole- 
cules, that from the molecular diameters it was possible to calculate 
the rate of diffusion, from the molecular volumes the variation from 
the law of Boyle, etc. etc., calculations which obivously are a mere 
retracing of the steps by means of which these quantities themselves 
were originally deduced. 
Such vagueness of thought with respect te a scientific matter is 
due no doubt almost entirely to the fact that the development of the 
conception from the days of Bernoulli down has been in the hands 
of professed mathematicians, men whose writings are unintelligible 
to all unfamiliar with the infinitesimal calculus, and lest we should 
deem it strange for men to take an interest in and even to hold 
pronounced views on a subject which from its very nature they 
could but unperfectly master, it is well to consider how few could be 
found in a large city capable of giving a satisfactory account of the 
grounds on which the prevalent views on the solar system are based, 
though fewer still perhaps doubt their substantial accuracy. The 
conceptions of the Kinetic theory were insensibly and vaguely ex- 
tended from the case of gases (for which alone they were first de- 
veloped) to include all state of matter: for do not liquids and solids 
expand on heating ? are not phenomena of diffusion as common among 
liquids as among gases: and should not the same process in the 
different cases be explained by the same mechanism? At the same 
time a certain enthusiasm on the part both of the developers of 
the theory and of their audience, added to the inability of most of 
the latter from want of a mathematical training, to take active part 
in the discussion, gradually led the teachers to teach and the hearers 
to accept the hypothetical premises of the theory as established 
facts ; the molecular world became a world of realities, and in striv- 
ing to reduce all physical phenomena to the interaction of the laws 
of motion and of attraction the Kinetic Theory posed as ‘‘the 
Astronomy of the infinitely small.’ Tyndall’s book was entitled 
“ Heat asa Mode of Motion.” O. E. Mayer, after much warning 
against “mere uncertain hypotheses,” says it is ‘‘ proved beyond all 
doubt” that heat isa kind of motion. And now in Canada in a book 
intended for the instruction of youth in our high schools in Ontario 
we find the conception of ‘‘ molecules” introduced in the first. 
