xxiv 
INTRODUCTION. 
fphere, and can pronounce with certainty, that the equili¬ 
brium of the glohe is effectually preferved, though the 
proportion 
I will not here run the riik of incurring M. Le Monter's difpleafure, by calling the ac¬ 
curacy of M. Bouvet’s obfervations in queftion ; but will admit every thing that he him- 
felf can think due to the inftruments and obfervations of that deferving navigator. It is 
enough for my argument, and it is but too evident, from the obfervations themfelves, that 
ours were by no means capable of determining the variation to fo fmall a quantity as that 
which M. Le Monler refts his whole caufe upon ; and if fo, his arguments, which depend 
wholly on a fuppofltion, that not only they, but M. Bouvet’s alfo, were capable of deter¬ 
mining it with the utmoft exadtnefs, muft fall to the ground. 
ift, It appears, from various inftances, that the variations obferved by the lame com- 
pafs would differ 3 0 to 5 0 , 6°, and fometimes even ro°, from no other caufe whatever, but 
putting the {hip’s head a contrary way * *. 
2d, That the fame compafs, in the fame fituation in every refpedf, within a few miles, 
but at two different times of the fame day, would give variations differing from one ano¬ 
ther, 3 0 , 4 0 , 5 0 , 6°, and even j° f. 
3d, That the fame compafs, on the fame day, and in the hands of the fame obferver, 
will give variations differing from one another by 5 0 , on board the fame {hip, when under 
fail, and when at anchor in a road-ftead 
4th, Compafles, made by the fame artift, at the fame time and place, but on board dif¬ 
ferent {hips, differed 3 0 , 4 0 , and even 5 0 in the variation §. 
5th, I he fame Compafles, on board the fame {hip, and within a few miles of the fame 
fituation, but at different times of our being there, gave variations differing by 4 0 and 5 0 , 
®r upwards ||. 
6th, Different 
* See the Original Aftronomical Obfervations, made in the fecond Voyage, March 11, 
* 773 > P- 37 2 : January 24, 1774, p. 375. and July 28, p. 378. 
f Obfervations in the fecond Voyage, February 2, 1773, p. 371. and January 19, 1775, 
p. 382. Alfo Obfervations in lad Voyage, July 17, 1776, p. 179. Auguft 30, p. 181. 
January 24, 1777, p. 192. and September 15, 1778, p. 205. 
J Aftronomical Obfervations of fecond Voyage, July 14, 1775, p. 385. 
§ Compare the Aftronomical Obfervations, made in the fecond Voyage, Auguft 3, and 9, 
and September 4, 1772, p. 181. with thofe of the fame dates, p. 369. Thofe of January 
11, and 14, and February 7, 1773, p. 182, with thofe of the fame dates, p. 371. Alfo 
Aftronomical Obfervations, made in the laft Voyage, of December 27, 1776, p. 191. Fe¬ 
bruary 22, 1778, p. 201. May 5, and 8, p. 102. July 9, and 24, 1779, p. 209. and 
January t6, 1780, p. 212. with thofe of the fame dates, p. 291, 293, 294, 297, 
and 298. 
fj Compare Aftronomical Obfervations, made in the fecond Voyage, February 10, p. 375. 
with Obfervations of December 11, 1774, p. 381. Alfo Obfervations, made in the laft 
Voyage, May 3, and June 18, 1779, p. 208. 
