128 NOTES OF A BOTANICAL TOUR 
The summit, or rim, of the Caldeira varies from 1,200 to 
1,500 feet above its base; the height of the most elevated 
point of the rim (which is also the loftiest part of the whole 
island of Fayal) being 3,170 feet above the sea, and the base of 
the Caldeira, consequently, about 1,670 feet above the sea. 
During our stay near Fayal, this Caldeira was scarcely ever 
clear from clouds or mist for an entire day; and, mostly, it 
was completely enshrouded during the day, though, not 
uncommonly, clear for some hours at night, or very 
early in the morning. Rain falls here frequently, while the 
lower parts of the island are perfectly dry and sunny; and 
when no rain is actually descending, the vegetation is often 
bedewed with moisture from the heavy mists. 
'The depth of this small valley, and the prevalence of mists 
over it, must necessarily reduce its share of sunshine to a very 
slender allowance; while its high;and steep walls probably cause 
an almost constant calm at the base, though the winds of the 
Atlantic may be sweeping vehemently over their summit. 
Add to these peculiarities, a plentiful supply of humidity 
from the streams and spray of waterfalls, coursing down wo 
deep gulleys that are formed in the walls, and it will readily — 
be conceived that the Caldeira is exactly the spot for a , 
natural Fernetum. Indeed, so numerous are the Filices here, 
that they give quite a character to the landscape, hanging in 
profusion about the rocks and waterfalls, and covering the 
more gradual declivities, among the various evergreen shrubs 
which clothe great part of the sides of the Caldeira, at least 
in the lower portion of it, for the shrubs gradually become 
scattered and stunted in the higher parts of the walls, and 
finally cease near their summit; as was remarked to be the 
case on the much more gradual ascent from Flamingos to the 
rim of the crater outside. I made no separate list of the plants 
seen in the Caldeira, which are almost all of them found also 
in the various ravines of the mountains around it outside; 3 
but the great advantage to a botanist is, that they are hee = 
collected into a small space, so that he can, in one day - 
within the Caldeira, find the species which would occupy his — 
