14 
POPULAR SCIENCE REVIEW. 
diameter instead of a lens, and with a modification of the double 
pile arrangement used by Lord Eosse. Only one pile was really 
used, but it was so mounted that both faces were similarly exposed 
to atmospheric influences. The results confirm Lord Eosse’s 
conclusions that the moon has no cosmical or internal heat to 
give us ; that the heat she does impart varies as the phase of 
illumination; and that the lunar is to the solar radiation as 1 
to 80,000. Further than these, Marie-Davy infers that the 
diffusive power of the moon’s surface is about the same as 
that of chromate of lead, as determined by MM. Desains and 
Provostaye, and that the moon’s heat, by reason of its large 
proportion of obscure rays, is much more impressionable by 
atmospheric humidity than solar heat. He found that, with the 
moon at the same age, his measured heat in November was 
six times as great as in October. He ascribes this excess to the 
use of a mirror instead of a lens, and concludes that the latter 
absorbs six times as much lunar caloric as the former. f 
* “Comptes rendus,” lxix. p. 1154. 
DESCKIPTION OF PLATE LIV. 
A A. Converging beam from great reflector. 
B B. Small concave mirrors (fixed upon a bar screwed to the eye end of 
the telescope ), one of them receiving the beam and condensing it upon the 
corresponding pile. 
C C. The two piles, each composed of four pairs of bismuth and antimony 
plates ; the faces exposed to the mirrors being laterally sheltered by metal 
cones, and their posterior faces covered with brass caps filled with water 
for maintenance of nearly uniform temperature. 
D D. Wires leading to the galvanometer. 
E. Reflecting galvanometer formed of a, a coil of fine wire surrounding b, 
a delicate magnetised needle covered by a small plane mirror, suspended by 
a filament of silk, and rendered partially astatic by the second small magnet 
c, rigidly connected with it. d is a large arched magnet sliding upon a ver- 
tical bar ; its use is to adjust the zero of the needle and regulate its sensitive- 
ness. 
F. Lamp. A beam from its flame passes through a hole in the board G 
and falls upon the mirror at b, thence being reflected on to a graduated scale 
on the opposite side of G. The displacement of the light-spot is a greatly 
magnified measure of the needle’s deflection. 
