972 
not followed by the declaration that the 
weight of a body can be and is changed 
without changing its mass, some curious 
experimental evidence being furnished to 
prove this. The conservation and dissi- 
pation of energy are denied and the splendid 
researches of Kelvin and Joule are over- 
hauled and denounced by critics who de- 
clare that ‘‘ Pressure is ‘ work’ and so is 
It is declared that Joule could 
not have obtained the same result for the 
motion.”’ 
mechanical equivalent of heat had he used 
mercury instead of water, and still less had 
he used friction on copper, iron, glass or 
wood, even though the ‘work’ expended 
were the same. Here the authors seem to 
be troubled by some sort of a notion of spe- 
cific heat, and throughout the whole discus- 
sion the reasonably well-informed reader 
cannot fail to be astonished at the unparal- 
Their 
own idea of heat is that itis ‘merely a state 
leled density of honest ignorance. 
or quality of bodies, which can be aug- 
mented or diminished, and which is due to 
the states of coercion, 7. ¢., when bodies are 
prevented from satisfying their natural ten- 
dencies.’ Their right to speak authorita- 
tively on this subject is further exemplified 
in the remark that in the case of a falling 
body ‘‘the amount of heat generated will 
vary as the bodies striking against each 
other are harder. A quantity of water or 
mercury falling from a certain height would 
not generate as much heat as would a like 
quantity of, say, steel falling from an equal 
height.” 
reflected in the statement that thin wires 
Some notions about electricity are 
offer less resistance than thick wires of the 
same material, and the further statement, 
SCIENCE. 
[N. S. Von. VI. No. 157. 
not altogether consistent with this, that the 
resistance of six pounds of copper would be 
the same, whether only a yard in length 
or a mile; also in the statement that the 
‘ air between two poles of an electro-magnet 
can be excited sufficiently to be felt as a 
viscous fluid when a piece of metal is passed 
to and fro between the poles.” 
The extension of some of these unrecog- 
nized laws into the domain of astronomy 
affords the authors ample opportunity for 
In the 
ease of the earth the whole thing is very 
the display of their peculiar logic. 
simple. Its axial motion is due to relative 
states of excitation of its two hemispheres 
divided meridianally ; the motion of the 
vanes of a radiometer and of plants turning 
Tits 
change of seasons is due to a reciprocating 
to the sun is sufficient evidence of this. 
motion originating in the relative states of 
excitation of the two hemispheres, divided 
equatorially, and its varying distance from 
the sun is another reciprocating motion due 
to variations in the aggregate state of exci- 
tation of the whole mass. The revolution 
of the earth about the sun is a simple phe- 
nomenon, due to the rolling of one sphere 
upon the circumference of another, the 
necessary assumption that the real diame- 
ter of the whole earth must be over 500,000 
miles being no obstacle to the acceptance of 
so beautiful a hypothesis. 
It is, perhaps, in their review of the New- 
tonian law of gravitation that the authors 
reach a maximum in their phenomenal in- 
capacity for an intelligent discussion of the 
subject. They assume to disprove that law 
by asserting that according to it the attrac- 
tion at the equator ought to be greater than 
