416 
POPULAR SCIENCE REVIEW. 
THE CORRELATION OF PHYSICAL FORCES.* 
LTHOUGH this book is in its sixth edition, it is one nevertheless which 
we cannot dismiss with a few short sentences. It is unquestionably 
one of the most important works of the age ; and although there may be a 
few reasons for objecting to the style in which the author has expressed 
some of his views, we should at the same time exhibit our gratitude to the 
man who expressed those views when there was danger in holding them. 
It ought to be borne in mind that he who had the boldness to enunciate 
those opinions more than thirty years ago is now one of the Judges of the 
Court of Common Pleas, and that he has not had the time to keep himself 
au courant with the progress of modern science. We think, therefore, that 
allowance should be made — especially by those whose excessive learning 
compels them to look down upon anyone who has not mastered the few 
technicalities of the most modem leader — for the opinions of a man who 
simply claims a hearing for his hypothesis. Assuredly Sir. W. Grove can 
afford to despise some modern scientists who, having been taught 
in the principles which he was the first unquestionably to lay down, 
pretend to have a certain amount of contempt for his work, because in- 
deed it does not distinctly recognise a system of nomenclature which is essen- 
tially modern, and may even be itself expelled from science in due course. In- 
deed, we might almost say that Sir W. Grove’s opinions have now become 
recognised throughout the scientific world ; and we would express the belief 
that in no branch has the idea of correlation and continuity been so 
thoroughly accepted as in that of modern physiology — afact whichis perhaps 
due to the able advocacy of Judge Grove’s ideas by Dr. Carpenter. There 
is not the smallest doubt that the idea which runs through the book now 
before us is strictly and rigidly true. It may no doubt be difficult to prove 
it in many cases, though these instances become fewer year by year; but we 
have not the slightest doubt on the question whether any form of force is 
not a condition that may be, under other circumstances, converted into any 
other form. And this is, we imagine, what Judge Grove would have us 
believe. For instance, we look on mechanical force as convertible into heat; 
this as productive of chemical action ; and this, in its turn, as convertible 
into galvanic action, which then may be converted into the more ordinary 
force. We regard all the forces as being convertible into each other. Of 
course there is an apparent loss, but then this is only apparent ; and, as our 
engineering forces are being improved, we see this conversion of, let us say, 
heat into mechanical force being every day made with less loss of the original. 
But it was not so easy a matter to detect this conversion of one so-called force 
into another when Mr. Grove — as he then was — first took up this matter 
for consultation. Every man of science in England must be proud to have 
to own the discoverer of the correlation of physical forces as a fellow- 
countryman ; for unquestionably, great as may be his legal merits, the author 
* “The Correlation of Physical Forces.” Sixth Edition, with other Con- 
tributions to Science, by the Hon. Sir W. R. Grove, M.A., F.R.S., one of 
the Judges of the Court of Common Pleas. London : Longmans, 1874. 
