the Theory of Light and Colours. i 7 
i( distance ; but those of ether at a less distance than the hun- 
“ dred thousandth part of an inch. And, as in air the vibra- 
“ tions are some larger than others, but yet all equally swift, 
“ (for in a ring of bells the sound of every tone is heard at two 
“ or three miles distance, in the same order that the bells are 
“ struck, ) so, I suppose, the ethereal vibrations differ in big— 
“ ness, but not in swiftness. Now, these vibrations, beside their 
“ use in reflection and refraction, may be supposed the chief 
“ means by which the parts of fermenting or putrifying sub- 
“ stances, fluid liquors, or melted, burning, or other hot bodies, 
“ continue in motion/' (Birch Vol. III. p. 251. Dec. 1 675.) 
“ When a ray of light falls upon the surface of any pellucid 
“ body, and is there refracted or reflected, may not waves of 
“ vibrations, or tremors, be thereby excited in the refracting or 
“ reflecting medium ? — And are not these vibrations propagated 
“ from the point of incidence to great distances ? And do they 
“ not overtake the rays of light, and by overtaking them sue- 
“ cessively, do not they put them into the fits of easy reflection 
“ and easy transmission described above ?” (Optics. Qu. 17.) 
“ Light is in fits of easy reflection and easy transmission, 
“ before its incidence on transparent bodies. And probably it is 
“ put into such fits at its first emission from luminous bodies^ 
“ and continues in them during all its progress/’ (Optics. 
Second Book. Part III. Prop. 13.) 
MDCCCII. 
D 
