432 On Refraction. 
 any,bending of .the rays of light bring the object nearer, to the 
. eye?” . A satisfactory demonstration of the reason why it should 
appear so, may be found in almost every elementary treatise on 
, optics ; but from what he expresses in the next passage, it ap- 
» pears that it would require something else than either mathema- 
_tieal, or, ocular’ demonstration to satisfy him. “ If,” says he, 
<¢.we bend a piece of iron wire, we certainly shorten the length 
it extended; but if the rays of light were so bent, they would fall 
short of the object!” What Dr. R.’s opinions may be of the 
manner in which light is transmitted, is not easy to guess; but 
. I should suppose them to be quite as original as some of his other 
views: at all events, he certainly cannot suppose that it is either 
by a continued stream of particles from the luminous body, or 
by an agitation of the intervening medium, or he could never 
_talk of comparing the rays of light to pieces of wire, or any other 
substance, of adeterminate length. It therefore appears that his 
objection proceeds entirely from some peculiar metaphysical no- 
tions of the nature of light, and not from any absurdity which he 
can demonstrate to exist in either the reasoning or results of the 
old doctrine; and should he ohoose to communicate those ideas, 
-we.may have an opportunity of combating him with his own 
weapons. Pas 
But let us now proceed to what follows, where he pretends to 
have demonstrated by experiment the identity of reflection and 
_ refraction. The passage which it will be necessary tu quote, is as 
follows : 
“ Having placed a piece-of money at the bottom of a wine- 
glass, I made the edge of it intercept my view; on pouring in 
a small quantity of water, the shilling seemed to rise; I now 
perceived two images of the object, one at the bottom, and the 
other floating at the top of the water, very apparent when the 
_glass was a little inclined to the eye. This floating image was 
agitated by every movement of the water. To ascertain whether 
this image was the real cause of vision, I held the glass above my 
eye, and saw the image floating by reflection on the surface of 
the water as if reflected from the face of a mirror. Further to 
convince myself that it is this floating image we see, and not the 
shilling at the bottom of the vessel, I brought my eye on a line 
with the image, and then gently lowering the glass, at the same 
time keeping my eye intently fixed on it, I saw the image by 
transmitted rays.”’ ' 
It happens rather unfortunately for Dr. R.’s doctrine, that this 
experiment, on which the whole of it is founded, is, of all others 
that he could possibly have hit upon, the best calculated to ex- 
-pose its absurdity. If he had only observed, in making the ex- 
periment, that when the glass was slightly shaken so as to agitate 
the 
