140 ARCTIC VOYAGES. Chap. V. 



says, the boisterous weather they had was accom- 

 panied by very vivid lightning, which is particu- 

 larly unusual in high latitudes in winter, and by 

 the frequent appearance and continuance, for seve- 

 ral minutes at a time, of balls of fire at the extremi- 

 ties of the yard-arms, and mast heads ; of these 

 not less than eight were counted at one time. 



All the experiments were carefully gone over in 

 London, and examined by the Council of the Royal 

 Society and Board of Longitude, with other indi- 

 viduals most conversant in these observations ; and 

 with the calculations for determining the variations 

 in the length of the seconds pendulum ; from 

 whence the following general deduction is drawn 

 for indicating the ellipticity of the earth, which is 

 all that can be given here, the various calculations 

 and the experiments occupying a large volume. 

 The result then is: — 39,01520 inches is the length 

 of the equatorial pendulum ; 0, 20245, the increase 

 of gravitation between the Equator and Pole ; and 

 the ellipticity -^. That deduced from the in- 

 crease of gravitation between London and Melville 

 Island was ^ 



312.6* 



Thus, says Captain Sabine, " the attempt to de- 

 termine the figure of the earth, by the variations 

 of gravity at its surface, has been carried into full 

 execution on an arc of the meridian of the greatest 

 accessible extent, and the results which it has pro- 

 duced are seen to be consistent with each other, in 

 combinations too varied to admit a probability of 



