Astronomical and Nautical Collections. 103 



p. 33, that supposing the mean density to be, according to the expe- 

 riments of Maskelyne and Cavendish, about 5.4; the mean super- 

 ficial density must be 3 • 08, which is rather greater than could have 

 been previously conjectured; the modulus of elasticity 10,800,000 

 feet, a little exceeding that of glass or of iron. This excess, however 

 is not sufficient to afford any very decided argument in favour of the 

 existence of a central fire, since it is very probable that the mo- 

 dulus increases when the compression becomes extreme, even 

 without any elevation of temperature. The central density, from 

 the same little table, is found 13*95, or somewhat greater than 

 that of quicksilver. 



The length of the pendulum vibrating seconds at the various 

 stations of Captain Sabine's experiments is found in page 333, re- 

 duced to the level of the sea, upon a probable supposition of the 

 general density of the superficial parts of the earth, as suggested 

 by Dr. Young, which would only require a very slight modification 

 from the present determination of j-Jg , as the comparative super- 

 ficial density. 



Latitude. Length in a vacuum 



Stations. reduced to the 



O / // level of the sea. 



St. Thomas 24 41 N. 39-02074 



Maranham 2 31 43 S. 39*01214 



Ascension 7 55 48 S. 39*02410 



Sierra Leone ..... 8 29 28 N. 39*01997 



Trinidad . 10 38 56 N. 39*01884 



Bahia 12 59 21 S. 39*02425 



Jamaica 17 56 7 N. 3903510 



New York 40 42 43 N. 39*10168 



London 51 31 8 N. 39*13929 



Drontheim 63 25 54 N. 39*17456 



Hammerfest 70 40 5 N. 39*19519 



Greenland 74 32 19 N. 39*20335 



Spitzbergen 79 49 58 N. 39*21469 



The results of different combinations of these experiments with 

 others, page 352, are expressed in this table : 



