On Refraction. 431 
can be no doubt that the specimens now in the Museum were 
in a much better state when they were first discovered ; and the 
most perfect even, and those the coarsest in their texture, must 
have been greatly injured during the 69 years that they have been 
exposed to the atmosphere. I found that a fragment of a brown 
MS. kept for a few weeks in a portion of air confined by mer- 
eury, lad caused the disappearance of a considerable part of the 
oxygen, and the formation of much carbonie acid. 
LXXXVI. Remarks on Dr. REave’s Paper on Refraction. By 
Mr. Cuarces Stark, of Portsmouth. : 
To Dr. Tilloch. 
Sir, — Tx the Number of your Magazine for October, I observe a 
paper by Dr. Reade, on the subject of Refraction, wherein a very 
determined attempt seems to be made to evertiitri the whole 
doctrine of Dioptrics, and to explain all the phenomena of optics 
on the principle of reflection alone. If he should really succeed 
in the accomplishment of this design (which he seems to antici- 
pate with no small degree of confidence), an important zra will, 
no doubt, be formed in the history of science, and an inevitable 
death blow given to those standard works on the subject, which 
have been so long adopted in our schools and universities. How 
far the Doctor is likely to succeed in effecting such a revolution, 
is my object here to inquire. 
In the formation of any new theory, or in the determination 
of a general law in philosophy, such as the one under conside- 
rat‘on, it may be presumed that the author, before publishing it 
to the world, would have observed the utmost degree of caution, 
not only in establishing the reasonableness of the hypothesis it- 
self, but also in submitting it to the test of repeated and varied 
experiments, so as to be found not only consistent with itself, but 
successful in all its applications. In this respect, no theory has 
ever been employed, in any department of Natural Philosophy, 
‘with more complete success than that which Dr. R. is here en- 
_ deavouring to explode. In reviewing the arguments, however, 
which he has brought forward in its refutation, and also those 
advanced in support of his own, it will require but little ingenuity 
of reasoning to show that his time and Jabour have been spent to 
very little purpose. , 
r.R. commences his paper hy endeavouring to refute the 
explanation that is usually given of the common optical experi- 
ment of placing a piece of money at the bottom of an empty 
vessel, and its seeming to rise higher as water is poured into it. 
He objects to the common explanation by saying: ‘ How can 
any 
