THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



♦ 



[FOURTH SERIES.] 



MARCH 1853. 



XXV. New Experiments on the Mean Density of the Earth. 

 By F. Reich*. 



I OUGHT perhaps to apologise for returning to a subject 

 which has been ah'cady submitted to so fundamental an 

 examination, that it may seem superfluous to enter upon its 

 further consideration. From observations made by me, and 

 published in a short paper in 1838, the mean density of the 

 earth was found to be almost exactly what Cavendish found it, 

 viz. 5*45. According to a far more elaborate investigation by 

 Baily it amounts to 5'66. Baily^s experiments have been con- 

 ducted with so much care, and are so very numerous, that the 

 value of mine in comparison with them is evanescent. These, 

 however, agree so well among themselves, as to render it pro- 

 bable that the difference between us is to be referred to the defi- 

 ciency in point of number of my observations ; and Baily him- 

 self has been kind enough tof-be^tow considerable attention upon 

 this difference, without, however, being able to ascertain its 

 cause. The conjecture expressed by him, that I perhaps have 

 omitted some less coincident observations, I must state to be not 

 correct. 



It may be easily conceived that I also have occupied myself in 

 endeavouring to render an account of this difference; and I 

 believe that I have discovered its origin to be attributable to 

 two circumstances. 



The first is the treatment of the results obtained immediately 

 from observation, which treatment has been more correctly con- 

 ducted by Baily than by me ; this will be rendered most evident 

 by an example. When, for instance, four observations were made, 



* Poggendorff's Annalen, vol. Ixxxv. p. 189. (Extract from a memoir 

 in the Math, and Phys. Class of the Royal Society of Sciences in Leipzie.) 

 Phil, Mag. S. 4. Vol. 5. No. 31. March 1853. M 



