374 NATURAL PHENOMENA OF THE EQUATORIAL REGIONS. 



to that of Quito, which answers to 20 in. 1 line [21*4 in. 



Eng.], and other places still higher, where the barometer 



falls to 17 in. 4 1. [18-47 in. Eng.]. 

 Hygrometrical I n his hygrometrical observations Mr. Ton H. sometimes 



used Saussure's hygrometer, sometimes Mr. De Luc's; but 



all his results were reduced to the degrees of Saussure's, 



correcting them for temperature. 

 Moisture on the On the summit of the Andes, where the hygrometer falls 



summit of the to 3 1 '7°, there still remains great moisture:' and the fresh- 

 Andes. . f . 



ness retained by the vegetation sufficiently proves, that it 



derives from aqueous vapour the aliment, that supports it 

 amid extreme drought. 

 Height of The aqueous vapour, which exhibits itself in large masses, 



clouds. seems to maintain nearly a constant height. From the mea- 



sures of Mr. von H. the lower stratum appears to support 

 itself at 1169 met. [1277 yards], and the higher at 3300 

 [3606 yards] above the level of the sea. As to those little 

 clouds, which are vulgarly termed flocks [rhoutons~\, it is 

 very remarkable, that they commonly rise to the height of 

 more than 7800 met. [8524 yards]. 

 Quantity of Mr. von II. estimates the quantity of rain, that falls an- 



rain - nually between the tropics, at more than 1*89 met. [74*36 



in.], while in Europe it is only 0*48 [18*88 in.*]. 

 Electricity of The electromedical table exhibits several equally curious 

 the atmosphere. resu jt s# The electric intensity increases considerably as you 

 approach the summit of the Cordilleras. The equatorial 

 regions from the sea to the height of 2000 met. [2186 yards] 

 are but slightly charged with the electric fluid ; it accumu- 

 lates in the clouds however, and there causes frequent ex- 

 plosions. They recur periodically, in general two hours 

 after the culmination of the sun; and their violence in these 

 Hail. climates is well known. At the height of 3000 met. [3278 



* This is certainly much too small. A mean for 11 different 

 places in England for 1809, see Journal, XXV, p. 309, gives 

 31*15: this is near Mr. Daltou's mean for all England, taking first 

 a mean of the counties: and a mean of several places on the con- 

 tinent, as well as in England, from the table in Dr. Young's Na- 

 tural Philosophy, vol. II, p. 477, gives 32*1. C, 



yards] 



