Astronomy. 155 
first mentioned intensity will therefore amount to 3000 337 units 
for each degree of differential temperature ; while for the low in- 
tensity it will be = =0°080 unit for each degree of differential 
temperature, Consequently, the ratio of the radiating energy will 
337 : 
= (030 +21 times greater at 3,000° than at 65°. spe M. 
Vicaire, on the authority of Dulong, states that the ratio will be a 
hundred fold greater for an increase of only 600°. According to 
i i n 
of energy increases several thousand times when the temperature 
18 Increased from 65° to 3,000°. Newton, then, as our experi- 
ments prove, is incomparably nearer the truth than the French 
;.Perimenters; and possibly future research will prove that 
the emissive power of cast iron is relatively greater in a state of 
fusion than when solid, or merely incandescent. This observed 
. 
temperature, and the totally different conditions of the radiators, 
the observed discrepancy is not too great to admit of satisfactory 
hation, 
aS ati 
we fallacy of Dulong’s formula relating to high temperatures 
having been it wi necessa 
1 lge to be discussed in this article. It should, however, be men- 
ped that the result of the measurement of solar intensity March 
1872, before referred to, proves the correctness of our peas 
demonstrations, showing that the temperature of the surface of the 
“Un is at least 4,036,000° F.—Wature, April 25. 
