524 Notices of Books. (October, 
withstanding the torrent, stirred by its tyrant’s paddles; all these 
great, minute, and wondrous; all these most curious and ad- 
mirable works of an Almighty Designer and Creator, who 
governs by compensation, and tempers compensation by insti- 
tuting a maximum of enjoyment through a minimum of 
suffering; who maintains His creations by the law of self- 
preservation: all these, and multitudes of other benignant fore- 
thoughts, these busy physiologists overlook, neither thinking, 
nor asking, nor, they give us reason to imagine, caring to know 
‘Whose works are these?’ Nay, more! while they are loqua- 
cious of acids and salines, they forget to think out or to ask 
‘Whose works are these?’ Who made acids and salines ? 
And while they trace ‘the human animal,’ for such they account 
man to be, and such they would make him, to the askidion or 
the monad, they consider not, and forget to ask, ‘ Who made the 
monad and the askidion ?’” 
The Correlation of Physical Forces. Sixth Edition. With other 
Contributions 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, Green, and Co. 1874. 
WE are very glad to welcome a sixth and revised edition of Sir 
W. Grove’s celebrated Essay. By “revised” we mean simply 
that those discoveries in Science which bear upon the subject of 
the relationship of the physical forces made since the first ap- 
pearance of the Essay, in 1843, have been added, and the whole 
has been thus rendered more complete. It may be said that the 
Essay has done its work, that scientific men fully realise the 
correlation of the physical forces, which has been so wonderfully 
exemplified during the last thirty years by the science of thermo- 
dynamics, but the Essay still remains a model of accurate rea- 
soning, and of an elegant scholarly style, and will always be 
studied with advantage by the student of Science. We need 
not give a very detailed account of its object; it is too well 
known to require that. But, in brief, the design is to show that 
if we take the so-called physical forces,—motion, light, heat, 
electricity, magnetism, and chemical affinity,—each one is 
capable of producing the remaining five ; and, further, from first 
to last the author combats the idea of such hypothetical entities 
as ethers, subtle fluids, &c., which have been devised to account 
for phenomena otherwise not easily explained. He endeavours 
to show that each and allof the physical forces is an affection of 
matter, not matter itself,—that, in fact, it is a mode of motion; 
and this idea, now fully admitted in the case of heat and light, 
will, no doubt, in our generation be extended to electricity and 
magnetism. 
Without giving any very connected chain of reasoning in a 
