INTENSITY OF LIGHT DEPENDS ON REPUIJ5IVE FORCE. 67 



effects of pressure, may we not conclude that it possesses 

 actual weight, although from its incalculable levity it may, 

 to some, appear the reverse at present ? We may therefore, 

 from analogy, presume to affix to the rays of light a ratio cor- 

 respondent to that of the particular original elementary matter 

 of which it is here submitted they are composed, to enable us 

 to judge whether the vigour of their respective action may not 

 be, in some degree, influenced thereby; and whether such 

 may controvert or support the present hypothesis. 



The intensity of the illuminating power of light seems to 

 depend on the energy of repulsive force, which is governed 

 by pressure, the effect of which is proportional to gravity. 

 Now the comparative space occupied by the original rays in 

 the spectrum, obtained by the triangular prism, is as follows : 



Red, 58.5. Yellow, 91.5. Blue, 210. 



These multiplied by the respective specific gravities of each 

 of the bodies they severally represent, give the proportionate 

 intensity of their illuminating powers, thus : 



Red, 9.360. Yellow, 12.810. Blue, 2.10. 



On the nature of light, two different theories have been 

 proposed: the first by Huygens, adopted by Euler, "That 

 light is a subtile fluid, filling space and rendering bodies 

 visible by the undulation into which it is thrown ; that w T hen 

 the sun rises it agitates this fluid ; these agitations gradually 

 extend themselves ; at last, striking the eye, we see the sun." 



The second by Newton, and others, " That light is a sub- 

 stance consisting of small particles constantly separating them- 

 selves from luminous bodies, moving in straight lines, and 

 rendering bodies luminous by passing from them and entering 

 the eye." 



It is presumed it can be shown that both of these theories 

 are in part reconcilable by the present hypothesis. 



F 2 



