60 FRAGMENTS OF SCIENCE 



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 

 molten condition. It would doubtless also apply to the 

 luminous fogs formed by the condensation of incandescent 

 vapors. In such cases when the curve representing the 

 radiant energy of the body is constructed, the obscure ra- 

 diation towers upward like a mountain, the luminous radi- 

 ation 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 

 attained a certain width of swing. In solid and molten 

 bodies a certain amplitude cannot be surpassed without 

 the introduction of periods of vibration, which provoke 

 the sense of vision. How are we to figure this? If per- 

 mitted to speculate, we might ask, Are not these more rapid 



