DENSITY OF THE EARTH. 27 



results could by no means be represented in every case by a 

 variation in the force of gravity in the ratio of the square of 

 the sine of the latitude. The English government decided, 

 therefore (at the recommendation of the Yice-President of 

 the Koyal Society, Davies Gilbert), on sending out a scien- 

 tific expedition for the extension of the inquiry at stations 

 far more widely removed from each other, which was entrusted 

 to my friend Edward Sabine, who had previously accompanied 

 Captain Parry, on his first Arctic expedition of discovery, as 

 astronomer. He visited in the years 1822 and 1823, for 

 the purpose of pendulum experiments, the West Coast of 

 Africa from Sierra Leone to the Island of St. Thomas near 

 the equator, Ascension, the coast of South America from 

 Bahia to the mouth of the Orinoco, the West Indies, and 

 New York, and subsequently the high Arctic north as far 

 as Spitzbergeri, and a previously unvisited part of East 

 Greenland, concealed behind formidable icy barriers, in 

 lat. 74 32'. This brilliant and successfully executed under- 

 taking had the advantage of being directed to a single sub- 

 ject of research as its principal object, and of comprehending 

 points extending over 93 degrees of latitude. 



The field of observation along the French arc was indeed 

 less near to the equinoctial and Arctic regions, but it had the 

 great advantage of a linear distribution of the places of obser- 

 vation and of direct comparison with the curvature found by 

 the geodesical and astronomical operations. Biot, in 1824, 

 continued the series of pendulum experiments from Eormen- 

 tera in 38 39' 56" lat., where he had previously observed 

 with Arago and Chaix, to Unst, the northernmost of the 

 Shetland Islands, in 60 45' 25"; and in conjunction with 



