336 EXPERIMENTS AT SPITZBERGEN. 



Mean . . 86469*68 



Correction diff. Temp. 44 48°— 36° 7 — 4'97 



„ diff. of Arc 1° 65 (1-463) 2 — (1-366) 2 —0-45 



„ diff. of Elevation 474 feet —0*18 



86475-28 



These observations at Spitzbergen are reduced 

 to the same arc, temperature, and elevation, 

 above the sea, as the means between the cor- 

 responding ones in London, before and imme- 

 diately after the voyage. The number of vi- 

 brations being 8638245 ; thermometer 48° ; 

 barometer 29*62 ; arc 1° 463. A further cor- 

 rection is also due to the buoyancy of the at- 

 mosphere, arising from the difference between 

 the atmospheric pressures at each place ; but, 

 as this difference is exceedingly small, and the 

 correction subject to some uncertainty as to its 

 amount, and, moreover, much less than the 

 unavoidable errors which arise from irregulari- 

 ties in the action of the maintaining power, 

 friction, &c, it is omitted. 



Taking the length of the seconds' pendulum in 

 London (at the level of the sea) to be 39-13929, 



The length at Spitzbergen is 39*2132 

 Polar length . . 39.2199 



Equatorial length . . 39-0117 



Polar compression, or ellipti- 

 city of the earth, ^-J-g- 



Lap. Mec. Celeste, torn. ii. p. 102. 



