77 
barometrical measurement the highest of its 
summits to be 4088m. (2097 toises) above the 
level of the sea^ which exceeds by 400 metres 
that of the peak of TenerifFe. I sketched the 
mountain from the vicinity of the great town of 
Perote^ in the arid plain covered with pumice 
stone, which we crossed in ascending from Vera 
Cruz to Mexico. The summit of the Coffer is a 
naked rock^ surrounded by a forest of pines. 
On climbing this summit, I remarked, that the 
oaks disappeared at the height of 3165 metres 
(1619 toises); but the pines, which in their 
leaves resemble the 'pinus strobus, are seen at the 
height of 3942 metres (2202 toises). Under 
each zone, the temperature and barometric pres- 
sure prescribe to the vegetable world the limits, 
which it cannot pass. 
