384 NOTES OF A NATURALIST. 



mometer was, in round numbers, 1° C. for every 200 metres of 

 ascent, while in ascending from the sea-level to the plateau of 

 Quito the fall was proportionately less, being at the rate of 1° C. 

 for 226 metres. On the other hand, the fall of temperature was 

 more rapid in ascending from Quito to the higher peaks. On 

 an average of all the ascents, we may reckon the rate of 1° for 

 180 metres. But it is remarkable that, taking the average of 

 the three peaks which rise about 2000 metres above the level 

 of Quito, the temperature fell only at the rate of 1° for 195 

 metres, while in ascending to peaks higher by nearly 1000 

 metres, the rate of fall was 1° for 176 metres, and if we take 

 the still higher summit of Chimborazo we may reckon the rate 

 of fall at about 1° for 160 metres. 



The apparent increase in the rate of decline of temperature in 

 the higher region is still more clearly shown if we compare the 

 mean of the three peaks whose average height is 4946 metres, 

 with that of the two whose average height is 5905. For a 

 difference in the mean height of 959 metres, we find an average 

 fall of 6" 5 8° C, or a fall of 1° for 145 metres. Takhig the first 

 ascent of Chimborazo as giving the most probable results, we 

 find that between this peak and the mean of the three lower 

 summits, with a difference in height of 1307 metres, the difference 

 of temperature is 973°, or a fall of 1° for 134 metres. Again, 

 comparing Chimborazo with the mean of Cotopaxi and Cayambe, 

 we find, for a difference of height of 348 metres, a difference of 

 temperature of 3' 15°, or a fall of 1° for 1 10 metres. 



I am fully aware that these observations are not numerous 

 enough to lead to any safe general conclusions ; the com- 

 paratively high temperatures found at the height of about 5000 

 metres may be due to exceptional local conditions, such, for 

 instance, as the ordinary formation of clouds at about that 

 level ; but, so far as they go, the observations tend to negative 

 the supposition that in the tropics the rate of decrease of 

 temperature diminishes as we ascend to the higher regions of 

 the atmosphere. 



MM. Reiss and Stubel made numerous observations in the 

 Andes of Ecuador and Peru, during a prolonged visit to that 

 region. Lists of heights obtained by reduction from their 

 observations have appeared in various German scientific 

 periodicals, and more fully in the American Journal of Science, 



