VOL. VII.] PHILOSOPHICAL TRANSACTIONS. IQ 



supposed, yet I undcrstaiul as little, why it should be split at so small an angle 

 only, and not rather spread and dispersed through the whole angle of refraction. 

 And further, though I can easily imagine how unlike motions may cross one an- 

 other; yet I cannot well conceive how they should coalesce into one uniform 

 motion, and then part again, and recover their former unlikeness; notwithstand- 

 ing that I conjecture the ways by which the animadversor may endeavour to 

 explain it. So that the direct, uniform and undisturbed pulses should be split 

 and disturbed by refraction ; and yet the oblique and disturbed pulses persist 

 without splitting or further disturbance by following refractions, is to me as unin- 

 telligible. And there is as great a difficulty in the number of colours, as you 

 will see hereafter. 



But whatever be the advantages or disadvantages of this hypothesis, I hope I 

 maybe excused from taking it up, since I do not think it needful to explicate 

 my doctrine by any hypothesis at all. For if light be considered abstractedly 

 without respect to any hypothesis, I can as easily conceive, that the several 

 parts of a shining body may emit rays of different colours and other qualities, of 

 all which light is constituted, as that the several parts of a false or uneven string, 

 or of unevenly agitated water in a brook or cataract, or the several pipes of an 

 organ inspired all at once, or all the variety of sounding bodies in the world 

 together, should produce sounds of several tones, and propagate them through 

 the air confusedly intermixt. And, if there were any natural bodies that could 

 reflect sounds of one tone, and stifle or transmit those of another; then, as the 

 echo of a confused aggregate of all tones would be that particular tone, which 

 the echoing body is disposed to reflect; so, since, even by the animadversor's 

 concessions, there are bodies apt to reflect rays of one colour, and stifle or 

 transmit those of another; I can as easily conceive that those bodies, when 

 illuminated by a mixture of all colours, must appear of that colour only which 

 they reflect. 



But when the objector would insinuate a difficulty in these things, by allud - 

 ing to sounds in the string of a musical instrument before percussion, or in the 

 air of an organ bellows before its arrival at the pipes ; I must confess, I under- 

 stand it as little, as if one had spoken of light in a piece of wood before it be 

 set on fire, or in the oil of a lamp before it ascend up the match to feed the 

 flame. 



You see therefore, how much it is beside the business in hand, to dispute 

 about hypotheses. For which reason I shall now in the last place proceed to 

 abstract the difficulties in the animadversor's discourse, and, without having re- 

 gard to any hypothesis, consider them in general terms. And they may be re- 

 duced to these 3 quaeries : 



D 2 



