1874.] Notices of Books. 527 
consequently, motion is produced, and it is decomposed, there- 
fore chemical action is produced.” ‘This is a kind of tutti, after 
each one has been singing his solo. 
Few words are used more loosely and indefinitely than the 
word Nature; it is sometimes called ‘the principle which pro- 
duces all things;”’’ hence, poetically, the ‘* Universal Mother,” 
** Madre Natura,” &c. We remember to have read, in one of the 
older numbers of the ‘ Philosophical Transactions,”—‘ By 
Nature I understand the works of God manifested in Creation ;” 
then we talk about the “laws of Nature,” the “works of 
Nature,” &c. Sir W. Grove says (p. 152)—‘‘ The word ‘ Nature’ 
is still more personified; instead of being used to denote, what 
alone it can denote,—namely, things as we see, hear, or feel 
them, and their relations ascertained by comparison and abstrac- 
tion,—Nature is treated as a sort of Superintending Angel, who 
enjoins this, permits that, and forbids the other.” Finally, as to 
matter and force, he says—‘‘ The evidence we acquire of the 
continued existence of matter is by the continued exertion of the 
force it exercises, as, when we weigh it, our evidence of force 
is the matter it acts upon. Thus matter and force are correlates 
in the strictest sense of the word; the conception of the existence 
of the one involves the conception of the existence of the other: 
the quantity of matter, again, and the degree of force, involve 
conceptions of space and time.” 
The Address ‘‘On Continuity,” which has already reached a 
third edition, was delivered by Sir W. Grove, as President of the 
British Association, at Nottingham, in 1866. It is, to our mind, 
quite a model of what a President’s Address should be. Not a 
vehicle for the exclusive advocacy of Darwinism and free thought, 
but a resumé of the whole aspect of Science at that particular 
time, and an allusion to all the more dominant phases of thought 
which then prevail, and to the more prominent discoveries and 
generalisations. ‘These are interspersed with his own far-seeing 
and luciferous ideas :—-‘‘ As Phlogiston,” he says, ‘‘and similar 
creations of the mind have passed away, so with hypothetic 
fluids, imponderable matters, specific ethers, and other inventions 
of entities, made to vary according to the requirements of the 
theorist, I believe the day is approaching when these will be dis- 
pensed with, and when the two fundamental conceptions of 
matter and motion will be found sufficient to explain physical 
phenomena.” 
The remainder of the work (that is to say, half of it) contains 
Sir W. Grove’s researches in experimental science. Commencing 
with the nitric acid battery, now so well known and so much 
used, and which was devised in 1839, we find, in succession, the 
gas battery, the decomposition of water by heat, the striz in the 
electrical discharge, and the effects of heat on fluids. There are 
many other papers, all containing a good deal of suggestive 
matter, and hints as to new researches. 
