%fy% Examination of Si. Pierre's IJypo/be/is 



differed widely from the calculation : for, not only the dura- 

 tion of total darknefs was extremely fhort, but the reft of the 

 duration, previous and pofterior to the total objuration, was 

 {till fhorter, as if the figure of the earth was elliptical, having 

 the fmalleft diameter under the equator, and the greater from 

 pole to pole. 



Navigators in the north have always feen the elevation of 

 the fun above the horizon greater the nearer they approach 

 the poles. It is impoffible to afcribe thefe optical effects to 

 atmofpherical refraction. 



Barents, on the 24th of January, in Nova Zembla, faw 

 the fun 1 5 days (boner than he expected, which would give a 

 refraction of 2^°; a thing impoffible, and the circumftance 

 can be afcribed to no other caufe than his real elevation. 



St. Pierre aits the difficulty arifing from the different vi- 

 brations of the pendulum, by observing that they arc liable 

 to a thoufand errors. 



The elongation of the poles being thus demonftrated, the 

 Current of the feas and tides follows as a natural and Decenary 

 confequence. 



Let us now confider the extent of the polar ices, and the 

 powers capable of effecting their folution. 



The polar ices in the winter proper to each hemifphere are 

 from fix to feven thoufand leagues in circumference; but in 

 their fummer, from two to three thoufand. 



The ices and fnows form in our hemifphere, in January, a. 

 cupola, the arch of which extends more than two thoufand 

 leagues over the two continents, with a thieknefs of fome 

 lines in Spain, fome inches in France, feveral feet in Ger- 

 many, many fathoms in Ruffia, and beyond the6o° of north 

 tat. of fome hundred feet. Some ice iflauds were feen by 

 Ellis from fifteen to eighteen hundred feet above the level of 

 the fea, and they pn on increafing to the pole to a 



height indel c. Hence the enOi ■ 1-? nation of 



water, fixed by the cold, of winter in our hemifphere, above 

 the level of the ocean, id ciearlv perceptible; and to the pe- 

 riodical fufion of thefe vaft maffies the general movement of 

 the fcas and tides is juftly afcribahle. The ices at the fouth 

 pole exceed in quantity tuofe at the north ; and two fuch 



bodiei 



