40 FRAGMENTS OF SCIENCE. 
Appearance Energy of 
of spiral. obscure rays. 
Dark 1 
Dark 6 
Faint red * 10 
Dull red 13 
Red 18 
Full red 27 
Orange 60 
Yellow 93 
White 122 
Here, as in the former case, the dark arid bright radi- 
ations reached their maximum together; as the one aug- 
mented, the other augmented, until at last the energy of 
the obscure rays of the particular refrangibility here chosen 
became 122 times what it was at first. To reach a white 
heat the wire has to pass through all the stages of invisible 
radiation, but in its most brilliant condition it embraces, 
in an intensified form, the rays of all those stages. 
And thus it is with all other kinds of matter, as far as 
they have hitherto been examined. Coke, whether brought 
to a white heat by the electric current, or by the oxyhydro- 
gen jet, pours out invisible rays with augmented energy, as 
its light is increased. The same is true of lime, bricks, 
and other substances. It is true of all metals which are 
capable of being heated to incandescence. It also holds 
good for phosphorus burning in oxygen. Every gush of 
dazzling light has associated with it a gush of invisible 
radiant heat, which far transcends the light in energy. 
This condition of things applies to all bodies capable of 
being raised to a white heat, either in the solid or the mol- 
ten condition. It would doubtless also apply to the lumi- 
nous fogs formed by the condensation of incandescent 
vapors. In snch cases when the curve representing the 
radiant energy of the body is constructed, the obscure 
radiation towers upward like a mountain, the luminous 
radiation resembling a mere "spur" at its base. From 
the very brightness of the light of some of the fixed stars 
we may infer the intensity of that dark radiation, which is 
the precursor and inseparable associate of their luminous 
rays. 
We thus find the luminous radiation appearing when the 
radiant body has attained a certain temperature; or, in 
other words, when the vibrating atoms of the body have 
