THE REASON WHY : 



" The swiff acttmlly performs what has been in these 

 enlightened times disproved of the bird of Paradise ; except the 

 small time it take- in sleeping, and what H devotes to incubation, 

 every other action is done on the wing." PENNANT. 



720. The edible birds' nest of the extreme east of Asia have given rise to much 

 speculation, and their composition is still a matter of doubt. They are found 

 attached to the sides of cliffs, and the roofs of caverns opening upon the sea-coasts. 

 But whether their substance; is derived from the gastric glands of the swallows, or 

 collected by the latter from the sea-shore, or elsewhere, it is impossible to say 

 authorities being equally divided upon the point." In outward appearance, the 

 esculent swallow's nest resembles that of the chimney swallow, being concave, 

 shallow, and lined with feathers ; but the crust, or shell, instead of being made of 

 clay is something in appearance like the fine manna of commerce, or isinglass. Fine 

 filaments appear to be cemented together by a transparent viscous matter, not 

 unlike what is left by the sea upon stones alternately covered by the tide, or those 

 gelatinous animal substances found floating upon every coast.* 



About twenty-seven thousand pounds weight are annually exported from Java, 

 and about thirty thousand tons of Chinese shipping are engaged in the traffic. The 

 danger attendant upon the collecting of the nests in the awful caverns is described 

 as being imminent in the extreme. 



721. Why does the swift rarely alight on level ground? 



Because, owing to the extreme shortness of the feet, and the 

 disproportionate length of the wings, the bird cannot rise from a 

 fiat surface,, since its body is not sufficiently elevated to admit of 

 the downward stroke of the wings. Whenever the swift does 

 alight, therefore, it is always in such places as present a brink or 

 declivity, from the edge of which it can launch itself. 



722. How do swifts, which seldom alight on the ground, gather 

 the materials for their nests ? 



It has been conjectured that swifts gather the materials by 

 raising them as they glance along the ground, in the same way 

 that they drink by skimming over the surface of the water. 

 Others suppose that these birds catch the substances in the air 

 as they are carried up by the wind. Whilst the more common 

 and generally received opinion is, that the materials are purloined 

 from the nests of sparrows and swallows. 



723. This latter surmise is corroborated by several circumstances : first, the swift's 

 nest consists of nearly the same substances as the sparrows; secondly, we know 

 that swifts enter sometimes into the nests of small birds, which w may suppose 



* Sir G. Staunton. 



