107 



ed, that the circular summit of the peak of Te- 

 nerifFe is only a hundred toises in diameter. Ac- 

 cording to the measures I made at Riobamba, in 

 1803, the dome of the Chimborazo, 153 toises 

 below it's summit, consequently in a point which 

 is 1300 toises higher than the peak, is still 673 

 toises (1312 metres) in breadth. The zone of 

 perennial snows also forms a fourth of the height 

 of the mountain ; and the base of this zone, seen 

 on the coast of the Southern Ocean, fills an ex- 

 tent of 3437 toises (6700 metres). But though 

 Chimborazo is two thirds higher than the peak, 

 we do not see it, on account of the curve of the 

 globe, at more than 38 miles and a third farther*. 

 The radiant brilliancy of it's snows, when at the 

 port of Guayaquil, at the end of the rainy sea- 

 son, it is discovered at the horizon, may lead us 

 to suppose, that it must be seen at a very great 

 distance in the South Sea. Pilots highly worthy 

 of credit have assured me, that they have seen it 

 from the rock of Muerto, to the south-west of the 

 isle of Puna, at a distance of 47 leagues-f-. When- 



* Without attending to the refraction, the Peak of Tene- 

 riffe (1904 toises) is visible at 1° 57' 22", Mount Blanc 

 (2440 toises) at 2° 13' 0", and Chimborazo (3350 toises) at 

 2° 35' 30". The mean refraction, supposed to be 0*08, aug- 

 ments this distance, as to Chimborazo, only fourteen miles. 



f According to the charts of the Deposito hydrografico of 

 Madrid. Admitting 1° 13' 32" for the difference of the 

 meridians of Guayaquil and Quito, such as I found it (Observ. 



