42 T)r Brewster and Dr Gordon ofi the Human Eye. 
is another head similar to that which was sent home last year. 
Mr Belzoni, when in Nubia, a few months ago, opened a temple 
at Ipsamhool, which he describes as being the largest excavation 
dther in that country or in Egypt, containing fourteen large 
chambers, and an immense large hall, with eight colossal statues, 
thirty feet high, and four others in the sanctuary, all perfect. 
The walls were covered with hieroglyphics, and the colours in 
high preservation. 
You will easily imagine how highly pleased I was with this 
little tour, which occupied, most agreeably and usefully, about^ 
forty days, which I must otherwise have spent either at Cairo, 
or on board the ship in the harbour of Suez. 
Art. VI. — Experiments on the Structure and Refractive Power 
of the Coats and Himours of the Human Eye. By David 
Brewster, LL.D. F. R. S. Lond. & Edin., and the late 
John Gordon, M. D. F. R. S. Edin Communicated by 
the Author. 
Having disco\?ered a very remarkable structure in the crys- 
taihne lenses of fishes and quadrupeds, by exposing them to 
polarised light -f, I was anxious to examine with care the or- 
ganization of the cornea, the iris, and the crystalline of the hu- 
man eye. My friend, the late Dr Gordon, who had studied 
with much success the structure and functions of this important 
organ, took a deep interest in the inquiry, and was so kind as 
to procure for me an eye a few hours after death, and to pre- 
pare, by dissection, the different parts of it that I wished to ex- 
amine. From the great difficulty of obtaining this organ in 
such a fresh state, he suggested the propriety of embracing the 
opportunity which was thus offered to us, of obtaining cor- 
rect measures of the different parts of which it is composed. 
The aqueous and the vitreous humours had hitherto been sup- 
posed to have the same refractive power as water ; and even 
Dr Wollaston, the most accurate of our experimental philoso- ' 
* An account of the experiments contained in this paper was read before 
the Iloyal Society of Edinburgh on the 3d of February 1817. 
t Phil. Trans. Lond, 1816, p. 311. 
