i88o.] 
( 727 ) 
CORRESPONDENCE. 
* * The Editor does not hold himself responsible for statements of fa&s or 
opinions expressed in Correspondence, or in Articles bearing the signature 
of their respective authors. 
“THE DISESTABLISHMENT OF THE SUN.” 
To the Editor of The Journal of Science. 
Sir, Referring to the work bearing the above title, noticed in 
your August number, it seems to me that neither the author nor 
your reviewer has given full weight to one fa 6t. The former 
argues that if the poles are cold because the sun’s 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. To 
this erroneous conclusion your reviewer merely replies : — “ He 
forgets that at the poles the sun’s rays are absent for one-half 
the year entirely, and fall during the other half 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 
all very well ; but both you and the author overlook the fadt that 
in places in the torrid zone where vegetation is wanting, and the 
absence of watery vapour in the air gives full scope to the loss 
of heat by radiation,— e.g., in the Sahara, and in many parts of 
South Africa,— the cold in the night is very severe. There can 
be no doubt that if the return of the sun could be delayed but 
for a few hours, frost would be experienced in all arid regions 
within the tropics. I do not see how these night-chills can be 
explained on the author’s theory. 
As regards his assertion that glass is impervious to heat, how 
can he explain the arrangement adopted at all meteorological 
observatories ? The maximum temperature of solar radiation is 
observed by means of a thermometer placed horizontally on a 
wooden frame 5 feet from the ground, whose bulb is made of 
black glass, externally covered with fine lampblack, and enclosed 
in an outer and exhausted tube of transparent glass. This ar- 
rangement has been seledted not on theoretical principles, but 
in accordance with experiment. The author does not remember 
the diffeient behaviour of glass with radiant heat according as it 
is emitted from incandescent or non-incandescent bodies. The 
