[ 48 ] 



FOURTH OBSERVATION. 



The variations are confiderably fmaller in very elevated fitua- 

 tions than on the level of the fea. Thus Mr. Bouguer obfcrved 

 that while on the coafts of Peru the variations extended to i: of 

 an inch ; at Quito, elevated 9374 feet above the fea, they 

 reached only to 0,083 °f ^^ inch. Mr. Sauffure made fimilar 

 obfervations in Savoy, as did Mr. Lambert in Switzerland. 

 II. Sauff. Voy. aux Alpes, p. 577. 



FIFTH OBSERVATION. 



The mean height of the barometer on the level of the fea in 

 moft parts of the globe hitherto examined is about 30 inches. 

 Mr. Bouguer under the line obferved it at 29,908 inches; but 

 as his barometer was not purged of air by fire, it flood lower 

 than it fhould. Sir George Shuckburgh, on a mean of feveral 

 obfervations on the coafts of Italy and England, found it at 

 30,04, when the temperature of the 5 was 55°, and that of the 

 air 62°. In the proximity of the poles the annual mean heights 

 of the barometer differ much mere from this ftandard than in the 

 more fouthern parts of our hemifphere. 



As to the connedlion of the variations of the barometer with 

 the weather, the four following obfervations, made by Dr. Hallcy 

 in England, feem to be moft univerfal, as they were found by Mr. 

 Melander to apply to lat. 39° *, and by Mr. De Luc to lat. 46° f. 



• Schwed. Abhand. 1773, S. 255. 

 t 1 De Luc Modif. p. 77. 



SIXTH 



