[August, 
528 Analyses of Books. 
is a needless truism, if, as Mr. Bland holds, in perfect accordance 
with the commonly received theory, the temperature of our planet 
was greatly in excess of that at which water can exist. To deny 
the existence of air is another question. Surely the higher the 
temperature the more matter must have been present in a gaseous 
state. Our author forgets, also, that no one seeks to account 
for the lower temperature of the poles than that of the Equator 
by their greater distance. The theory of diredt and oblique rays, 
which he pronounces a “ myth,” is perfectly satisfactory. Sup- 
pose a number of parallel rays falling upon a given surface : the 
more such surface is defledted from a diredtion at right angles to 
the rays, the fewer of such rays fall upon each square foot of the 
surface. The author argues that if the poles are cold because 
the heat-rays fall upon them obliquely, a spot on the Equator at 
midnight ought to be colder still, because it is out of the sun’s 
rays altogether ! He forgets that at the poles the sun’s rays are 
absent for one-half the year entirely, and fall during the other 
half very obliquely and scantily upon the soil ; whereas at the 
Equator the surface of the soil has not time to cool down during 
a single night. This is, indeed, Mr. Bland’s main error : he 
seems to think that if the sun is the source of heat, the temper- 
ature of any place should depend solely upon its being above the 
horizon, or not, at any given moment. In consequence of this 
mistaken assumption he asks — How is it that the temperature 
often gets higher in the night ? and how is it there is not a great 
difference in the temperature when there is a total eclipse ? The 
first of these questions is solved by reference to a change in the 
wind : as to the second, a chilly feeling has been observed during 
an eclipse ; but the occultation is too brief, and extends over too 
small a part of the earth’s surface, to bring on, e.g., a frost. 
He asks, further, How is it that rivers become frozen on the 
surface rather than at the bottom ? We thought it was now 
generally known that water expands in freezing, and the ice 
formed, being specifically lighter, floats upon the surface. 
Again, “ How is it that the frost never penetrates more than a 
comparatively few feet into the earth ?” Because earth is a very 
poor conductor. But if any appreciable quantity of heat were 
emitted from the interior of the earth, how is it that ice buried a 
few yards in the ground may be preserved during a whole sum- 
mer, whilst if laid on the surface it melts in the first mild days of 
spring ? 
The author even asserts that the sun, so far from imparting, 
robs us of heat. He makes use of this hypothesis to explain 
away the eflecfts of a burning-glass. He says — “ If a burning- 
glass be held in the shade no change in the temperature is ob- 
served in its neighbourhood. If the shadow be removed an 
entirely different state of things is observed. The rays of heat 
that were lazily ascending straighten out .and quicken, as if en- 
dowed with life. The evidence that they straighten may be 
