t 267 ] 



VIII. An Examination of St. Pierre's Hypothejis refpecling 

 the Canfe of the Tide's, which, in oppejition io the received 

 Theory, attributes them to fuppofed periodical Effii/ions of 

 the Polar lees. By Samuel Woods, Efq. Read before 

 the Ajkefian Society November 5, 1799. 



I 



[Concluded from Page 147.] 



NOW proceed to ftate the three remaining proofs adduced 

 by St. Pierre in corroboration of the demonftration I have 

 juft noticed ; but, as I conceive myfelf to have fully difproved 

 the geometrical evidence, I (hall not trouble you with an at- 

 tempt to invalidate thefe fubfidiary confirmations; 



The fecond proof (fays he) is atmofpherical. It is well known 

 that, in proportion as you afcend amountain, the mercurv in the 

 barometer fubfides : now the mercurv finks in the barometer 

 in proportion as you advance northward. The weight of one 

 line of mercurv at Paris is equivalent to an elevation of 10 

 fathom and 5 feet, whereas in Sweden it is equivalent to 

 10 fathom 1 foot 6 inches only; and of courfe the ground of 

 Sweden mult be higher. From a fer'tes of obfervations made 

 by captain Cook in the fouthern hemilphere in T773 to 1775, 

 we perceive the mercury fcarcely ever nfes ' :gher than 29 

 inches bevond the 60th degree of fouth latitude, and mounted 

 ahnoit always to 30 inches and even higher in the vicinity 

 of the torrid zone; which proves that the barometer falls as 

 you recede from the line, and that both poles are elongated. 



The third proof is nautical, arifijig from the annual c!c- 

 fcent of the ices toward the line, impelled by currents pro- 

 ceeding alternately from each pole during their rcfpe£tive 

 fummers, immenfe mountains ol ice being frequently feen, 

 by navigators in low latitudes. 



The fourth proof is agronomical. Childrey (an Etfglifti 



author of note) fuppofes, as I do, that the earlh at the poles 



ivercd with ice to fuch a height as to render its figure 



fenlibly oval. Kepler fays that the eclipfe of the moon on 



ith September 1624, like the one obferved bv Tycho 



Brahc in 158s, which was total, and very nearly central, 



M Rl differed 



