526 Notices of Books. ‘October, 
matter, or as matter acting by attraction and repulsion in a 
definite direction.” 
The remarks to be found on pp. 106 and 107, relating to the 
finite nature of our intellects, are much to be commended to the 
notice of scientific men, at a time when perhaps as much as in 
that of the Greek Positivists, or more modern Encyclopedists, 
intellectual pride is the bane of too many otherwise great. 
minds :—‘‘ Men are too apt,” remarks our author, ‘‘ because 
they are men, because their existence is the one thing of all 
importance to themselves, to frame schemes of the universe as 
though it was formed for man alone: painted by an artist of the 
Sun, a man might not represent so prominent an object of 
creation as he does when represented by his own pencil.” 
Sir W. Grove often leads us from a purely physical to the 
verge of metaphysical discussion. In regard to the boundaries 
of the universe, he says—‘‘ We cannot conceive a physical 
boundary, for then immediately comes the question, What bounds 
the boundary ? and to suppose the stellar universe to be bounded 
by infinite space, or by infinite chaos, that is to say, to suppose 
a spot—for it would then become so—of matter in definite 
forms, with definite forces, and probably teeming with definite 
organic beings, plunged in a universe of nothing, i is to my mind, 
at least, far more unphilosophical than to suppose a boundless 
universe of matter existing in forms and actions more or less 
analogous to those which, as far as our examination goes, per- 
vades space.” 
The last of the physical forces which is considered is chemical 
affinity, of which it is truly observed that it is that mode of force 
of which the human mind has hitherto formed the least. definite 
idea. We think that the weakest part of this Essay is that in 
which the other'physical forces are said to produce chemical 
affinity: thus we read on p. 26—‘‘In the decompositions and 
compositions which the terminal points proceeding from the 
conductors of an electrical machine develope when immersed in 
different chemical media, we get the production of chemical 
affinity by electricity, of which motion is the initial source.” 
Again, light may effect chemical combinations and decomposi- 
tions, but it does not produce chemical affinity as a force; it 
simply determines a chemical change, or determines a mani- 
festation of chemical force, which had all along been existent in 
the bodies which undergo the change. We find, among the con- 
cluding remarks, a statement of instances in which some one 
force being disturbed, all the others appear:—‘‘ Thus, when a 
substance, such as sulphuret of antimony, is electrified, at the 
instant of electrisation it becomes magnetic in directing at right 
angles to the lines of electric force ; at the same time it becomes 
heated to an extent greater or less, according to the intensity of 
the electric force. If this intensity be exalted to a certain point 
the sulphuret becomes luminous, or light is produced: it expands 
