SWALLOW. 
507 
surrounded with rocks of gray limestone, or white 
marble. The nests are placed in horizontal rows, 
at different depths, from fifty to five hundred feet. 
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 by the uniform 
fineness and delicacy of their texture ; those that 
are white and transparent being most esteemed, and 
fetching often in China their weight in silver. 
“ These nests are a considerable object of traffic 
among the Javanese, many of whom are employed 
in it from their infancy. The birds, after having 
spent nearly two months in preparing their nests, 
lay each two eggs, which are hatched in about 
fifteen days. When the young birds become fledged 
it is thought the proper time to seize upon their 
nests, which is done regularly three times a-year, 
and is effected by means of ladders of bamboo and 
reeds, by which the people descend into the ca- 
verns ; but when these are very deep, rope ladders 
are preferred. This operation is attended with 
much danger, and several perish in the attempt. 
The inhabitants of the mountains generally em- 
ployed in this business, begin always by sacrificing a 
buffalo; which custom is observed by the Javanese 
on the eve of every extraordinary enterprise. They 
also pronounce some prayers, anoint themselves 
with sweet-scented oil, and smoke the entrance of 
the cavern with gum benjamin. Near some of the 
