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Art. XXXII.— SCIENTIFIC INTELLIGENCE. 
I. NATURAL PHILOSOPHY. 
ASTRONOMY. 
1. Heat discovered in the Moon's Rays. — The following inte- 
resting experiment was made by Dr Howard, by means of a 
differential thermometer of his own invention, (see this Journal , 
vol. ii. p. 383.) “ Having blackened the upper ball of my 
differential thermometer, I placed it in the focus of a 13 inch 
reflecting mirror, which was opposed to the light of a bright full 
moon. The liquid began immediately to sink, and in half a mi- 
nute was depressed 8°, where it became stationary. On placing 
a skreen between the mirror and the moon, it rose again to the 
same level, and was again depressed on removing this obstacle.” 
This experiment was repeated several times, in presence of some 
of Dr Howard’s friends, and always with the same result. See 
Silliman’s American Journal , vol. ii. p. 329. 
2. On the supposed Transit of the Comet of 1819 over the 
Sun. — We have already stated, (see this Journal , vol. ii. p. 379-), 
that General Lindener could see no spot on the sun on the 26th 
May 1819; but it appears from the observations of Professor 
Schumacher and Brandes, that the sun was by no means free 
from spots on that day; and Dr Gruithuisen and Professor 
Wildt agree in describing a small spot near the middle of the 
sun’s disc, which might possibly have been the comet, though 
certainly not so distinctly defined as a planet would have been. 
Bode’s Jahr. 1823. 
3. Volcanoes in the Moon.~—T)Y Olbers informs Dr Gauss, 
that he observed on the 5th February an appearance in the 
dark part of the moon, which has been called a lunar volcano, 
(see this Journal , vol. iv. p. 429.) It appeared as usual in 
Aristarchus. It was small, but much brighter than the other 
parts of the moon, unilluminated by the sun, quite like a star, 
and even appeared like a star of the sixth magnitude, seen si- 
tuated to the north-east of the moon. Dr Olbers is inclined to 
believe that this brightness is produced by the reflection of the 
light of the earth from an even and smooth surface of a great 
extent of rock in the moon. If it shall be found that the same 
