7 
and a few foxeS; wliich ate up the stragglers. The 
bison, in its migrations, still has the escort of grizzly 
bears and wolves in the region of the Rocky Mountains ; 
and the reindeer is described, by Admiral Von Wrangel, as 
being followed by the same animals in Siberia, in its vernal 
and autumnal migrations, 
“ On the Extent and Action of The Heating Surface for 
Steam Boilers,” by Professor Osborne Reynolds, M.A. 
The rapidity with which heat will pass from one fluid to 
another through an intervening plate of metal is a matter 
of such practical importance that I need not apologise for 
introducing it here. Besides its practical value it also forms 
a subject of very great philosophical interest, being inti- 
mately connected with, if it does not form part of, molecular 
philosophy. 
In addition to the great amount of empirical and practical 
knowledge which has been acquired from steam boilers, the 
transmission of heat has been made the subject of direct 
inquiry by Newton, Dulong and Petit, Pe'clet, Joule, and 
Rankine, and considerable efforts have been made to reduce 
it to a system. But as yet the advance in this direction has 
not been very great; and the discrepancy in the results of 
the various experiments is such that one cannot avoid the 
conclusion that the circumstances of the problem have not 
been all taken into account. 
Newton appears to have assumed that the rate at which 
heat is transmitted from a surface to a gas and vice versa is 
ceteris paribus directly proportional to the difference in 
temperature between the surface and the gas, whereas 
Dulong and Petit, followed by Pdclet, came to the conclu- 
sion from their experiments that it followed altogether a 
different law.^ 
These philosophers do not seem to have advanced any 
theoretical reasons for the law which they have taken, but 
have deduced it entirely from their experiments, “a chercher 
par tatonnement la loi que suivent ces resultats. 
* Traite de la Chaleur, Peclet, Vol. I., p. 365. 
t Ib., p. 363. 
