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POPULAR SCIENCE REVIEW. 
powerful ; but at tbe same time, while they show that the author has given 
serious attention to the question, they give us the idea rather of the “ special 
pleader ” than of one in search of truth. We, however, have no right to 
enquire into motives. The chief evidence in support of the current doctrine, 
is that which relates to Newton’s law of the gravitation of masses, to aber- 
ration, and to parallax. The value of each of these is discussed by A 
Wrangler, and, in his opinion, “ found wanting.” The law of gravitation he 
objects to on the ground that it is in great measure an hypothesis, since we 
cannot tell what may be the peculiar constitution of the heavenly bodies, and 
cannot therefore infer how gravity may act in each particular case : for it 
must be stated that A Wrangler has a pet hypothesis of his own, to the 
effect that the specific force of gravity may be different for different sub- 
stances. Aberration is, in his opinion, useless, because he thinks that it may 
be explained upon either supposition — that the earth moves round the sun, 
or the sun round the earth. Parallax is, he considers, equally unreliable, 
because it depends for correction on aberration ; and thus he annihilates all 
the testimony in which our poor credulous philosophers have been relying 
for so long a period. What, then, the reader will inquire, is the ultimate 
conclusion of this Iconoclast P We answer, none : he is merely an intel- 
ligent sceptic, who says you believe too much, for there are no logical 
grounds for your belief. We cannot afford the space to meet A Wrangler 
seriatim on all the points which he has raised ; but even admitting the 
possibility of both parallax and aberration being explicable on either 
hypothesis, we can fall back on Newton’s grand law, which A Wrangler 
has done nothing whatever to disprove, and we can say that it at once 
removes all of those doubts which the peculiarities of parallax and aberration 
tend, we confess, to engender. The way in which Sir John Herschel lays 
down the evidence on this grave question is characteristically lucid, and we 
cannot do better than refer our readers to the first chapter of his u Outlines,” 
for a simple and convincing expression of the evidence in support of the 
Copernican doctrine. In concluding his 77th paragraph, where he refers to 
the deficiencies of the testimony, he observes : “ The Newtonian theory of 
gravitation supplies this deficiency, and by showing that all the motions 
required by the Copernican conception must , and that no others can, result 
from a single intelligible and very simple dynamical law, has given a degree 
of certainty to this conception as a matter of fact, which attaches to no 
other creation of the human mind.” A Wrangler has failed to shake our 
belief in Newton’s law, since he has done nothing to show that the principle 
of gravitation is not universal ; and so long as we accept this law, so long 
must we give our faith, so far, to the system of Copernicus. 
MUSHROOMS AND TOADSTOOLS.* 
"1/FU SIIROOM-EATING humanity owes a never-ending debt of gratitude 
to Mr. W. G. Smith for the admirable work which he has just given 
* il Mushrooms and Toadstools : how to Distinguish easily the Difference 
between Edible and Poisonous Fungi.” With two large sheets, containing 
coloured figures of 29 edible and 31 poisonous species. By Worthington G. 
Smith. London: Ilardwicke. 1897. 
