372 Miscellanies. 
_ There are various bodies which, like insects, give reason to be- 
lieve that they possess a temperature somewhat different from that of 
the atmosphere : the same test establishes this fact. It is thus that 
a deviation of 50° is obtained by placing in the apparatus a ve: 
small piece of phosphorus, which, in contact with the most delicate 
thermometer, gives no indication of heat. 
he authors then endeavored, by this delicate instrument, to esti- 
mate the calorific influence of the lunar rays,—but so many unex- 
pected difficulties occurred in their attempts to remove the various 
causes of fallacy in the performance of this experiment, that they 
have not hitherto succeeded to their satisfaction. 
A slight modification of the apparatus enabled the authors to esti- 
mate the radiating, (émissif,) absorbing and reflecting powers of dif- 
ferent bodies. Mercury proved to have the highest reflective power 
among the metals; and the others followed in the order pointed out 
by Prof. Leslie. But one new fact which they ascertained is, that 
polish has very little effect in increasing the reflective power. Thus, 
in comparing the amount of reflected heat from a plate of brass, rough? 
from the casting, with a similar plate which had received the highest 
polish, a difference was apparent of only two degrees in thirty six. 
Their researches into the power of emanation only served to con- 
firm the laws already known; but the absorbent power furnished 
some remarkable results. 'The method of experimenting was this— 
the substance whose faculty of absorption was to be examined, was 
pasted to a disk of tinned iron, to the other side of which was fast- 
ened a stem perpendicular to the surface. After an exposure to the 
solar rays, these pieces were presented in pairs to corresponding sides 
of the instrument, and the magnetic index turned to the side of that 
which was most heated. As a counter proof, it was only necessary 
to change sides, and to ascertain the fact of a contrary movement. 
In this way the relative absorbing power was well ascertained, and 
the constant result was, that the absorbing power is precisely in the 
inverse ratio of the conducting power of the same substance. Thus, 
with respect to stuffs, the color being the same, the absorbing power 
was in the order of silk, wool, cotton, linen and hemp. The con- 
ducting power is just the reverse. So among the metals, the scale 
of conductibility, as is well known, is copper, silver, gold, steel, iron, 
tin and lead. The absorbing power, agreeably to the instrument, is 
exactly the reverse.. 
