On Refraction. 207 
Mr. Ware. has written an excellent paper.on the use and abuse 
of glasses. Perhaps it may be objected to the first experiment of 
this paper, that the piece of money radiated light as if from a 
centre or focus. To obviate which, I varied the experiment in 
the following manner: I first placed the piece of money at the 
bottom of the tumbler, and then placed immediately on it a con- 
cavo-concave lens; on filling in the water, I found the image 
formed, as already represented. I now placed a plano-convex 
jens over it, with the same results: here the rays were reflected 
toa focus, and consequently they could not answer for a refracted 
image. 
The theory of refraction and the retinal theory of vision are so 
intimately and inseparably united, that the one cannot exist with- 
eut the other. I therefore would request Mr. Stark to read my 
paper on Vision, published in a former Journal. If [I have ex- 
pressed myself with too much confidence, I must express my re- 
gret, and hope the learned and candid reader (for learning and 
candour generally go hand in hand) may attribute it to haste, 
perhaps not unaccompanied by a feeling of resentment at preju- 
dice and critical neglect. But, sir, Iam now happy to see that 
my opinions are daily gaining ground, and sanctioned by men of 
the first-rate abilities. I am certain both Mr. Stark and myself 
have one and the same object in view, the discovery of truth. 
I therefore shall endeavour, as far as lies in my power, to answer 
any particular objections, but must decline a metaphysical con- 
troversy on the nature of light; especially as the theory of New- 
ton or that of Des Cartes would equally answer for experimental 
inguiry. Disputatio torquet homines, says Cicero; and impressed 
with a high respect for that great orator, I would wish to avoid it. 
Epicurus thought that vision was produced by a continual suc- 
cession of material images sent to the eye, which at their first 
emission from the object are large, decreasing continually the 
further they go, till they arrive at such a smallness as will permit 
them to enter the eye. That images are sent off from bodies, 
ean easily be shown. And if I have shown that the rays of light 
coming from all points of an object, and meeting again at the 
focus, do not make a picture of the object on any white body in- 
terposed, then we have no other alternative than to go back to 
Democritus and Lucretius. 
I remain, sir, your obedient servant, 
- Cork, Feb. 26, 1822. Joserpa Reaper, M.D. 
XLVI. An 
