swallow and of its nest.

"In the Cass," says Sir George, "a small island near Sumatra, we found
two caverns running horizontally into the side of the rock, and in these
were a number of those birds' nests so much prized by the Chinese
epicures. They seemed to be composed of fine filaments, cemented
together by a transparent viscous matter, not unlike what is left by the
foam of the sea upon stones alternately covered by the tide, or those
gelatinous animal substances found floating on every coast. The nests
adhere to each other and to the sides of the cavern, mostly in
horizontal rows, without any break or interruption, and at different
depths from fifty to five hundred feet. The birds that build these nests
are small grey swallows, with bellies of a dirty white. They were flying
about in considerable numbers, but were so small, and their flight was
so quick, that they escaped the shot fired at them. The same sort of
nests are said to be also found in deep caverns at the foot of the
highest mountains in the middle of Java, at a distance from the sea;
from which source it is thought that the birds derive no materials,
either for their food, or the construction of their nests, as it does
not appear probable they should fly in search of either over the
intermediate mountains, which are very high, or against the boisterous
winds prevailing thereabouts. They feed on insects, which they find
hovering over stagnated pools between the mountains, and for the
catching of which their wide opening beaks are particularly adapted.
They prepare their nests from the best remnants of their food. Their
greatest enemy is the kite, who often intercepts them in their passage
to and from the caverns, which are generally surrounded with rocks of
grey limestone or white marble. The colour and value of the nests depend
on the quantity and quality of the insects caught, and perhaps also on
the situation where they are built. Their value is chiefly ascertained