Chap. VIII. PARRY'S THIRD VOYAGE. 273 



Sherer, Ross, and by Mr. Hooper, as observations 

 for determining the longitude : — 



By occupations of fixed stars. 



By fixed stars and the Moon — Foster. 



By transit of the Moon — Foster. 



By Jupiter's satellites — Foster. 



Magnetic dip of needle — Parry and Foster. 



Variation — Parry and various officers. 



The Board of Longitude having suggested that 

 one of the objects of the present voyage should be 

 the determination of the figure of the earth, by 

 means of the vibration of a pendulum, the appa- 

 ratus of Captain Henry Kater's construction was 

 supplied to the expedition, and placed in charge of 

 Lieutenant Henry Foster. As it was necessary that 

 the number of vibrations of the same pendulum 

 should be known at different places, Mr. Pond, the 

 Astronomer Royal, allowed the trial to be made at 

 Greenwich. The results of the experiments, as 

 stated by Lieutenant Foster, give briefly — 



Number of vibrations at Greenwich . . 86,159,434 

 Ditto at Port Bowes . . 86,230,242 



Length of seconds' pendulum in the 



latitude of Greenwich .... 39*13911 inches 

 Ditto at Port Bowen 39*203468 do. 



Whence, Mr. Foster says, the fraction expressing 

 the diminution of gravity from the pole to the 

 equator is -0054155, and 



The ellipticity of the earth ^-^. 



That of the French Geometricians^^. 



Sabine from the north 



289.1 



Sabine, Melville Island ~ 



312.6* 



