S9S Proceedings (^the Cambridge Philosophkcd Society, 
rotatory phenomena are the same with, or in some way de- 
pendent on, those which have operated in producing these sin- 
gular decrements. 
Mayl. — A paper by J. F. W. Hersohel, Esq. was read. 
On the actirni of Crystals with one axis on homogenemis light. 
The object of this paper is to shew, that among crystals mth 
one axis: of double refraction, the utmost diversity prevails in 
the scale of tints they develope on exposure to a polarised ray, 
and that their action in polarizing the differently coloured rays, 
is by no means proportional in all of them, or regulated by any 
simple or general law. The minerals confounded together un- 
der the common name of Apophyllite, are a strong example of 
this. In one variety of this body, the rays of all colours are 
polarized with nearly equal energy, the slight maximmn of 
action falling between the yellow and green. In a second, the 
polarizing energy descends rapidly from the red to the yellow, 
where it is almost insensible, and then rises still more rapidly 
to the violet, where it exceeds the action on the red. A third 
has a minimurtv and almost insensible action on the indigo, 
from which it increases rapidly on both sides of this colour, and 
is greater on the red than on the violet rays. These three va- 
rieties all exhibit circular rings, whose tints deviate enormously 
from Newton’s scale, (in which the action increases regularly 
from the red to the violet,) and were all found united and co- 
hering in a single crystal : another instance of deviation from 
Newton’s scale is produced in the hyposulphate of lime, (a 
crystal with one axis). From all these Mr Herschel concludes, 
that the law of proportional action on the differently coloured 
rays in all crystals is utterly unfounded, a conclusion to which 
be had been before led by observations on Rochelle salt. 
Art. XXIX.—SCIENTIFIC INTELLIGENCE. 
I. NATURAL PHILOSOl^KY. 
, ASTRONOMY. 
1. Observatory at Gottingen. — The new observatory at Got- 
tingen, which was some years ago completed under the direc- 
