71 
of the Radiation of Heat in the Atmosphere . 
The terrestrial radiation of caloric has been treated of at great 
length, and in a very interesting manner, in the latter part of the 
essay, and a comparison is also taken of the amount of noctur- 
nal radiation in different latitudes. It appears that the noctur- 
nal terrestrial radiation in the Torrid Zone falls short of what 
might have been expected ; from which Mr Daniell concludes, 
that the same cause which obstructs the passage of radiant heat 
in the atmosphere from the sun, opposes also its transmission 
from the earth into space. While we assent to the unexpected 
nature of these results, we do not think it necessary to insinuate, 
with M. Gay Lussac, that they were obtained at times when the 
air was less clear or less calm than at London. There are two 
circumstances which ought to have been taken into account, 
and which are sufficient of themselves to explain the anomaly. 
First, the high temperature of the soil, which, in the Torrid 
Zone, frequently retains a heat several centigrade degrees above 
that of the air, even when the latter has reached its minimum. 
The second and most efficient principle is the law which has been 
established by Mr Anderson, That the minimum temperature of 
the night is regulated by the constituent temperature of the 
aqueous atmosphere. The enormous quantity of moisture in 
the atmosphere equally prevents the diminution of its tempera- 
ture beyond a certain degree, and checks the cooling of the 
ground by evaporation. 
Art. XII. — Sketches of the Comparative Anatomy of the Or- 
gans of Hearing and Vision. By Thomas Buchanan, 
C. M., Author of the Illustrations of Acoustic Surgery, Sec. 
&c. Communicated by the Author *. 
1 .—Ear of the Squalus . 
rp ' 
JL HE organ of hearing, in the shark tribe, varies considerably 
from that of the human subject. 
We find neither ossicula auditus, tympanum, eustachian tube, 
nor cochlea ; but, as if to compensate for the want of parts so es- 
* Read before the Wernerian Society, 19th Nov. 1825. 
