54 Linntjean Society. — Asironoiitiad Sucieij/. 



In upwards of a hundred and twenty of these observations, 

 the error was not one second. 



For lurther details we must refer to the original commu- 

 nication. 



Jan. 20. — A paper on some improvements in the construc- 

 tion of the barometer, by J. F. Daniell, Esq. F.R.S. was read. 



Jan. 27. — A paper was read, on the anatomy of the mole 

 cricket; by John Kidd, M.D. F.R.S. 



LINN^AN SOCIETY. 



Jan. 18. — A further portion of the Rev. Messrs. Sheppard 

 and Whitear's catalogue of Norfolk and Suffolk birds was 

 read. 



ASTRONOMICAL SOCIETY. 



Jan. 14. — At the meeting this evening, Mr. Baily laid on 

 the table, for the inspection of the members, two micrometers, 

 which have been recently invented and constructed by M. 

 Frauenhofer, of Munich* . 



These micrometers are formed by means of very fine lines 

 cut on glass with a diamond point in a peculiar manner ; and 

 placed in the focus of the telescope. One of these microme- 

 ters consists of concentric circular lines drawn at unequal di- 

 stances from each other; and the other consists of straight 

 lines crossing each other at a given angle. The mode of 

 cutting these lines has furnished M. Frauenhofer with a me- 

 thod of illuminating them, which (at the same time that it 

 renders the lines visible) leaves the other part of the field of 

 the telescope in darkness : so that the transits of the smallest 

 stars may be observed by means of these micrometers ; the 

 lines appearing like so many silver threads suspended in the 

 heavens. A short account of the circumstances which led 

 M. Frauenhofer to this happy invention was read. 



An engraving of Frauenhofer's achromatic telescope, now 

 at Dorpat, of 14 feet focus and 9 inches aperture, was also 

 submitted to the inspection of the members present, by Mr. 

 Herscliel. 



A communication was read from Capt. Ross, dated Stran- 

 raer, 7th August 1824, in which he transmits a diagram ex- 

 hibiting his observation of the occultation of Herschel's planet 

 by the moon, on the preceding day, with Ramage's 25-feet 

 telescope, and a power of 500. The planet appeared to have 

 entered about one-third of its diameter on the dark part of 

 the moon before it disappeared, and its light began to dimi- 

 nish before it touched the lunar disc. On the contrary, at its 

 emersion it appeared one-fourth of its own diameter distant 



'Sec rhil. Mag. vol. Ixiv. p. 210. 



from 



