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266 Scientific Intelligence. 
velocity of rotation. Nevertheless, no generation of light or heat is ob- 
served on our globe, on Jupiter, or on the ring of Saturn. 
It might be thought that friction, though undeveloped in the case of 
the other celestial bodies, might engendered by the sun’s rotation, 
and that such friction might generate enormous quantities of heat. But, 
for the production of friction, two bodies, at least, are always necessa 
which are in immediate contact with one another, and which move with 
different velocities or in different directions. Friction, moreover, has a 
tendency to produce equal motion of the two rubbing bodies; and, w 
this is attained, the generation of heat ceases. If now the sun be the 
one moving body, where is the other? and if the second body exist, what 
power prevents it from assuming the same rotary motion as the sun 
_ But, could even these difficulties be disregarded, a weightier and more 
formidable obstacle opposes this hypothesis. The known volume and 
mass of the sun allow us to calculate the vis viva which he 
trusted by Kirchhoff, owing to the injury to his eyes in his former re 
searches. Hoffmann has the lines of numerous elements not be- 
fore recorded, and gives a table of the atmospheric lines, and their coin- 
cidences with the elements and with the lines produced by the electric 
spark in atmospheric air. 
3. An Improved Spectroscope—Analysis of the fixed line D; by 
Professor Jostan P. Cooxz, Jun. (Extracted, by permission, from 4 
letter to Dr. Percy).—I have had a spectroscope constructed, which I 
i lied 
the back of the prism are so adjusted that, when pushed against the 
wheel, the back of the prism is tangent to the circle. By means of 
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