Mr. Baily on the Mean Density of the Earth. Ill 



(Gerber's Anatomy, p. 31); some of the corpuscles, just like 

 misshapen blood-discs, are seen on their edges ; others appear 

 mottled, and one exhibits three nuclei. Many minute circular 

 molecules are seen in the fibrine ; they were generally from 

 7U.lr(jo tft to TT,n^o tno ^ an mcn m dmmeter, but their appearance 

 has not been at all clearly preserved in the engraving. B. The 

 same washed with dilute acetic acid ; the nuclei of the corpuscles 

 and the minute molecules are distinctly exhibited. Several of the 

 latter are attached to a corpuscle made very faint by the acid. 

 In fibrine obtained by washing from the blood of the ovipa- 

 rous vertebrata, there is also frequently an appearance of 

 minute fibrils, as shown at F, in fig. 2; but this fibrine is chiefly 

 characterized by its containing numerous particles similar to 

 and probably identical with the nuclei of the blood corpuscles : 

 these particles may often be seen in the fibrine without the 

 addition of any reagent, and acetic acid renders them very 

 plain, as at G in fig. 2. 



XIX. An Account of some Experiments with the Torsion- 

 rod, for Determining the Mean Density of the Earth. By 

 Francis Baily, Esq., F.R.S., Vice-President of the Royal 

 Astronomical Society *. 



THE author commences his account with a short prelimi- 

 nary history of the subject, and a reference to the previous 

 labours of Maskelyne and Cavendish. He considers the ex- 

 periments of Maskelyne, on the attraction of the Schehallien 

 mountain, by no means decisive of the question ; and with re- 

 spect to those of Cavendish, by means of the torsion-rod, he 

 is of opinion that Cavendish's object in drawing up his me- 

 moir was more for the purpose of exhibiting a specimen of 

 what he considered to be an excellent method of determining 

 this important inquiry, than of deducing a result, at that time, 

 that should lay claim to the full confidence of the scientific 

 world. For, Cavendish himself (who made only 23 experi- 

 ments), in allusion to this very point, expresses a doubt on the 

 subject, and hints at some further experiments which he had 

 in view, for clearing up some of the irregularities which he 

 had met with. But, as no further account of any subsequent 

 experiments is on record, and as no trace of any new light on 

 this subject can be found amongst Cavendish's papers, the 

 propriety and advantage of repeating the experiments, under 

 * From the Monthly Notices of the Royal Astronomical Society, having 

 been read May 13 and June 10, 1842'. An abstract of Mr. Baily's preli- 

 minary paper was given in Phil. Mag. Third Series, vol. xii. p. 233 : a 

 notice of M. Menabrea's paper on Cavendish's Experiments will be found 

 in vol. xix. p. 62. A translation of Laplace's memoir on the mean density 

 of the Earth, in which Cavendish's lesults are examined, was communicated 

 by Dr. Hutton to the First Series, vol. lvi. p. 321.— Edit. 



