6 REPORT—1850. 
He was thus induced to ascribe the circular structure to the cornea and the 
crystalline lens, in both of which he had found it to exist,—the yellow tint to the 
elastic capsule which he had found when in aq state of distension to depolarize the 
required yellow tint, and the analysis to the different membranes, such as the hya- 
loid, the membrane of Jacob, and other tissues which lie in front of the sensitive 
layer of the retina. The difficulty however which beset this explanation was, that 
the two yellow sectors, and the opposite pair of blue ones, should haye been in- 
clined 45° to the plane of primitive polarization, whereas they are parallel and per- 
pendicular to that plane. In order to account for this part of the phenomenon, it 
is necessary to suppose that the particles or minute crystals which radiate jon a 
centre are inclined 45° degrees to the radial line. 
On some new Phenomena in the Polarization of the Atmosphere. 
By Sir Davip Brewster, A.H., D.C.L., F.R.S. Lond. ὃ V.P.RS. Edin. 
In the brief notice given by the author of these phenomena, he ascribed the phzno- 
mena of atmospheric polarization to the joint effect of the light polarized by reflexion 
and by refraction, the light polarized by refraction compensating that polarized by 
reflexion at the neutral points of Arago, Babinet and Brewster, and showing itself 
separately when reflected from certain coloured clouds placed 90° from the sun. 
The author also pointed out, by means of a diagram, a method by which the pola- 
rizing condition of the whole atmosphere ma be determined by carrying round an 
unobstructed horizon a set of polarized bands kept in a perpendicular position by a 
level, and marking the azimuths of the different points where a compensation takes 
place at different times. The distances between these points will give the altitude 
of the neutral points, whether these points are above or below the horizon and 
invisible. 
Notice regarding the recent Improvements in Photography. 
By Sir Davip Brewster, K.H., D.C.L., F.RS. Lond. § ΚΡ... Edin. 
Sir David Brewster exhibited to the meeting a series of Talbotypes executed by the ' 
process invented by H. F. Talbot, Esq., and other processes which have since come 
into use. 
The earliest series of Talbotypes submitted to the meeting were a collection of one 
hundred executed in Scotland by D. O. Hill, Esq. and Mr. Robert Adamson, and 
which Mr. Hill had presented to Sir David Brewster. This series, and indeed all 
those taken under Mr. Hill’s superintendence, are distinguished by the artistic 
arrangements and drapery of the figures, a merit quite independent of their excel- 
lence as photographs. Hence these Talbotypes have been greatly admired and 
esteemed by artists, and have been justly regarded as valuable auxiliaries to art. — 
The second series was executed by Mr. Talbot's process by an amateur, Samuel 
Buckle, Esq. of Peterborough, and were distinguished by the fineness of their colour, 
the minute perfection of the picture in all its parts, and the peculiar beauty of the 
subjects which they represented. They consisted chiefly of views of Peterborough 
Cathedral, and the buildings connected with it. 
The third series was executed by Messrs. Ross and Thomson, Edinburgh, photo- 
graphers to the Queen, by the process in albumen invented by M. Niepce of Paris. 
They were the specimens referred to in the President’s Address*, and consisted 
chiefly of yiews of Edinburgh, and copies of pictures and statues. They, were con- 
sidered by all who saw them superior to any photographs that had been produced 
either in this country or on the continent. " 
In addition to these Talbotypes, Sir David Brewster exhibited two landscapes pro- 
duced by the gelatine process of M. Poitevin, which had been presented to him by 
M. Balard, Member of the National Institute of France. ate ann αν: 
* See an earlier part of this volume. 
