Astronomy. — Optics. 173 



6. Parallax of the Sun. — That able astronomer M. Encke of Gotha, 

 is about to publish an elaborate work on the Parallax of the Sun, as de- 

 duced from the Transit of 1769. The parallax obtained for the transit 

 of 1761 was between 8".429813 and 8".551237. The result of M. 

 Encke's computations is 8".5776. The semidiameter of the sun at his 

 mean distance is 858" 424. From the transit of 1639 he deduces the 

 motion of the node of Venus' orbit, which he finds to be 20".508. Ba- 

 ron Lindenau's Letter to Baron Zach, in the Corr. Astron. vol. x. p. 174. 



7. Copley Medal adjudged to Dr. Brinkley. — The President and Coun- 

 cil of the Royal Society of London have adjudged to that distinguished 

 astronomer the Rev. Dr. Brinkley the Copleyan Medal, for his able ob- 

 servations and papers on the parallax of certain fixed stars. 



8. Opposition of Ceres, Pallas, Juno, and Vesta.— The following are 

 the times of opposition of the four new planets : 



According to Mr. Groombridge, Pallas will probably appear like a star 

 of the eighth magnitude. Juno will be too near its aphelion in the in- 

 ferior part of its orbit to be visible with any illumination of the wires, 

 but its transit may be compared with fixed stars. The following are 

 some of the previous positions of these planets. 



Phil. Mag. vol. lxiv. p. 359. 



OPTICS. 



9. Singular Colour of the Sun. — On the 13th September, 1824, from 

 2 h p. m. to 5^ h p. m. the sun exhibited a very extraordinary colour, 

 which we never before observed, and have never seen mentioned by any 

 author. It was of a fine salmon colour, which it preserved for many 

 hours. The sky had a vapoury aspect ; but the sun was not surround- 

 ed by any halo or penumbra of any kind. The barometer stood at 29.74 

 inches, and the thermometer at 58;°. The wind was in the west, and was 



