THE VULTURE. 
27 
pour forth his sweet and vernal notes nearer to 
them. 
But to return to the vulture. After the repeated 
observations I have made in the country where it 
abounds, I am quite satisfied that it is directed to 
its food by means of its olfactory nerves coming in 
contact with putrid effluvium, which rises from 
corrupted substances through the heavier air. 
Those are deceived who imagine that this effluvium 
would always be driven to one quarter in the 
tropics, where the trade- winds prevail. Often, at 
the very time that the clouds are driving from the 
north-east up above, there is a lower current of air 
coming from the quarter directly opposite. This 
takes place most frequently during the night-time, 
in or near the woods ; and it often occurs early in 
the morning, from sunrise till near ten o'clock, when 
the regular trade-wind begins to blow. Sometimes 
it is noticed in the evening, after sunset ; and, now 
and then, during the best part of the day, in the 
rainy season. In Guiana there is a tree called hay- 
awa : it produces a deliciously smelling resin, fit for 
incense. When^the Indians stop on the banks of a 
river for the night, they are much in the habit of 
. burning this resin for its fine and wholesome scent. 
It is found in a hardened lumpy state, all down the 
side of the tree out of which it has oozed. It is 
also seen on the ground, at the foot of the tree, in- 
corporated with the sand. When we had taken up 
our nightly quarters on the bank of the Essequibo^ 
many a time we perceived this delightful fragrance 
of the hayawa, which came down the bed of the 
