433 
Natural Philosophy. ---^Optics. 
by the attraction of the rings on the motions of the satellites : 
to furnish formulae adapted to the determination of the elements 
of their orbits, and the constant co-efficients of their periodical 
and secular equations, from observation ; likewise to point out 
the observations best adapted to lead to a knowledge of such de« 
termination. The papers to be sent to the Society on or before 
the 1st February 1823.” The Council propose that each me- 
moir shall bear a motto, and that a sealed paper, having the same 
motto, shall contain the name of the author. The sealed papers 
of the unsuccessful candidates will be destroyed unopened, in 
the presence of the Council. . The remaining part of the Re- 
port contains an account of their pecuniary resources, which are 
in a flourishing state ; and a notice of the principal points to 
which the Council requested the attention of Captain Basil Hall, 
during his voyage to the South Seas. 
9. Geocentric Places of Ceres and Vesta. — The following are 
the geocentric places of Ceres and Vesta for the month of April: 
Ceres. Vesta. 
B. Asc. 
Decl. 
R. Asc. 
Decl. 
1821, April 1. 
16?^ 33' 
14° 37 S. 
7^22' 
26° 13 N. 
7. 
16 33 
14 40 
7 28 
26 3 
13. 
16 32 
14 43 
7 34 
25 51 
19. 
16 29 
14 45 
7 41 
25 37 
, — 25. 
16 27 
14 46 
7 48 
25 22 
See the Phil. Mag. 
vok Ivii. p. 129. 
OPTICS. 
10. Optical Structure of Melted Quartz. — In order to decide 
the important question relative to the existence of circular or 
rotatory polarization in the ultimate particles of Silex, which had 
been maintained by M. Biot, as a demonstrated result of his ex- 
periments I was anxious to examine the optical properties of 
a piece of quartz-crystal that had been fused. Upon mention- 
ing my wish to our eminent Professor of Chemistry, he kindly 
supplied me with a piece of considerable magnitude. This 
piece, which Dr Hope had reduced to fusion by the action of a 
stream of oxygen, is nearly two-tenths of an inch long, and 
* See this Journal^ vol. ii. p. 179, 180. ; and the present Number, p. 373. 
VOL. IV. NO. 8. APRIL 1821. ' E C 
