282 Analyses of Booh. t^APRlt, 



A remarkable eftect on the instrument was observed in level- 

 ling, which is thus described by Mr. Woodhouse : 



" The tube of the telescope is braced to the axis by four 

 tubes. The stations of the two persons who level are opposite, 

 and contiguous to the south-west and north-east braces. Being 

 in the constant habit of examining the meridian mark, in order 

 to know what degree of stability the instrument possesses, I 

 found, after levelling, that the south meridian mark was to the 

 east of the middle wire. In about 10 minutes the middle wire 

 returned to the meridian mark, and bisected it. 1 noted this 

 circumstance, a second, third, and fourth time, and then began 

 to inquire whether I had conjectured rightly in attributing it to 

 the expansion of the tubes or braces. For this end, I placed a 

 heated blanket across the south-west and north-east braces, and 

 found the meridian mark deviating to the east of the middle 

 ■wire : a contrary effect was produced by placing the blanket 

 across the south-east and north-west braces. In these trials the 

 object glass was towards the south : contrary effects took place 

 when it was turned to the north. 



" As yet I am unable to say whether or not the sun's rays 

 falling on the braces, during an observation of his transit, affect 

 the accuracy of the observation. I am inquiring into that point, 

 and have ordered a screen to be made to protect the braces from 

 the rays of the sun." 



XVIII. On the Fossil Elk of Ireland. By Thomas Weaver, 

 Esq. MRIA. &c.— (See A7mals for June, 1825.) 



XIX. Microscopical Observations on the Materials of the Brain, 

 and of the Ova of Animals, to show the Analogy that exists 

 between them. 



XX. is Mr. Faraday's paper on new Compounds of Car- 

 bon and Hydrogen, already reprinted in the Annals for January 

 and February of the present year ; and the two following articles 

 on magnetism developed by rotation, by Messrs. 13abbage, 

 Herschel, and Christie, we omit noticing in this place, for the 

 reasons already stated. 



XXIII. On the Annual Variations of some of the principal 

 Fixed Stars. By J. Pond, FRS. Ast. Roy. 



XXIV. On the Nature of the Function expressive of the Law of 

 human Mortality, and on a neiv Mode of determining the Value of 

 Life Contingencies. In a letter to F. Baily, Esq. FRS. by Ben- 

 jamin Gompertz, Esq. FRS. E. W. B. 



2. Memoirs of the Astronomical Society of London, Vol. II. 



Part I. 



The First Part of the Second Volume of the Memoirs of the 

 Astronomical Society of London has just been published ; and 

 the following are its contents :— ■ 



