XXVI ADVERTISEMENT. 



of three different fpecies. The two firil experi- 

 ments are taken from the annual defcent of the 

 ices of each Pole toward the Line ; the two fé- 

 cond, from the Currents which defcend from the 

 Poles during their fummer ; and the two laft, from 

 the rapidity and the extent of thefe fame Currents, 

 which perform the tour of the Globe alternately 

 during fix months : three are for the North Pole, 

 and three for the South Pole. 



The firft experiment, that deduced from the 

 defcent of the ices of the North Pole, is detailed 

 in the Firfl Volume of this Work, Study Fourth. 

 I have there quoted the teftimonies of the mod ce- 

 lebrated Navigators of the North ; particularly of 

 Ellis of England, of Lift/choîtefî and Barents of Hol- 

 land, OÏ îilarlens of Hamburg, and of Denis the 

 French Governor of Canada, who atteft, that thefe 

 ices are of a prodigious height, and that they are 

 frequently met with in the fprirg, in temperate 

 Latitudes. Denis affures us, that they are loftier 

 than the turrets of Notre-Dame, that they fome- 

 times form floating chains of more than a day's 

 failing, and that they run aground as far fouth as 

 the great bank of Newfoundland. The moft nor- 

 therly part of this bank hardly extends beyond 

 the fiftieth degree ; and mariners engaged in the 

 whale-fifliery, do not fall in with the folid ices, in 

 fummer, till they approach the 73tb degree. But 



oi\ 



