"On the third day the birds began to rear the side walls of the nest, after having rendered the bottom compact by repeatedly pressing the materials with their breasts, and turning themselves round upon them in all directions. They first formed a plain border, which they afterwards trimmed, and upon this they piled up tufts of cotton, which was felted into the structure by beating and pressing with their breasts and the shoulders of their wings, taking care to arrange any projecting corner with their beaks so as to interlace it into the tissue, and render it more firm. The contiguous branches of the bush were enveloped as the work proceeded in the side walls, but without deranging the circular cavity of the interior. This part of the nest required many materials, so that I was quite astonished at the quantity which they used.

"On the seventh day their task was finished; and anxious to examine the interior, I determined to introduce my finger, when I felt an egg that had probably been laid that morning, for on the previous evening I could see there was no egg in it, as it was not quite covered in. This beautiful edifice, which was as white as snow, was nine inches in height on the outside, whilst in the inside it was not more than five. Its external form was very irregular on account of the branches which it had been found necessary to enclose; but the inside exactly resembled a pullet's egg placed with the small end upwards. Its greatest diameter was five inches and the smallest four. The entrance was two-thirds or more of the whole height, as seen on the outside; but within it almost reached the arch of the ceiling above.

"The interior of this nest was so neatly worked and felted together, that it might have been taken for a piece of fine cloth, a little worn, the tissue being so compact and close, that it would have been impos

sible to detach a particle of the materials without tearing the texture to pieces; yet was this only effected by the process which I have already described; and it must be confessed that it was a work truly admirable, considering the instruments of the little mechanics *."

285

CHAPTER XV.

CEMENTERS.-AMERICAN CHIMNEY-SWALLOW. ESCU

LENT-SWALLOW.

ONE of the old classifications of birds ranged them in three divisions, the first comprehending those which muddled in the dust; the second, those which washed in the water; and the third, those which did both. A division, something upon the same principle, with regard to the building of nests, would comprehend, in the first class, birds which used no salivary cement; in the second, those which did; and in the third, those which used it only in a portion, not the whole of their structures. In no circumstance of nest-building has there been more error promulgated in books of natural history than with respect to this cement, few naturalists seeming to be even aware of its existence; but finding nests so neatly compacted, and their parts adhering firmly to one another as well as to walls and boughs of trees, authors think it requisite to name some adhesive material by which this is accomplished, and when there is no clay in the edifice, spider's web is the substance generally fixed upon. We do not indeed deny that both the webs of spiders and of the social caterpillars are partly employed by some birds; but this is by no means an occurrence common to all the small neatly built nests of our song-birds and some others, as we are taught in books to believe. As this very point involves one of the most curious discussions connected with the subject of nests, we

shall begin with one about which there can be the least dispute. We are furnished with an instance well adapted for this purpose in the American chimney-swallow (Cypselus pelasgius, LATHAM). This bird, with respect to appearance, may be readily distinguished from its congeners by its rounded tail, the shafts of which, extending beyond the vanes, are sharp pointed, strong, and elastic, and are em, ployed as a point of support for the body when the bird rests, as it exclusively does, upon the side of a tree or a perpendicular wall. It is also easily distinguished in the air by its long wings and short body, and its wide unexpected diving ra pidity of flight, shooting in various directions without any apparent motion of the wings, and uttering the sounds tsip, tsip, tsip, tsee, tsee, in a hurried manner. It is always most gay and active in wet and gloomy weather, and is the earliest abroad in the morning and latest out in the evening, of all its brethren.

Wilson has given the following very interesting, history of their mode of nestling. "They arrive," he says," in Pennsylvania late in April or early in May, dispersing themselves over the whole country, wherever there are vacant chimnies in summer sufficiently high and convenient for their accommodation. In no other situation with us are they observed at present to build. This circumstance naturally suggests the query, Where did these birds construct their nests before the arrival of Europeans in this country, when there were no such places for their accommodation? I would answer, probably in the same situations in which they still continue to build in the remote regions of our western forests, where European improvements of this kind are scarcely to be found; namely, in the hollow of a tree, which in some cases has the nearest resemblance to their present choice, of

any other. One of the first settlers in the state of Kentucky informed me that he cut down a large hollow beech-tree, which contained forty or fifty nests of the chimney-swallow, most of which, by the fall of the tree, or by the weather, were lying at the bottom of the hollow, but sufficient fragments remained adhering to the sides of the tree to enable him to number them. They appeared, he said, to be of many years' standing. The present site which they have chosen must, however, hold out many more advantages than the former, since we see that in the whole thickly settled parts of the United States these birds have uniformly adopted this new convenience; not a single pair being observed to prefer the woods.

Security from birds of prey and other animals, from storms that frequently overthrow the timber, and the numerous ready conveniences which these new situations afford, are doubtless some of the advantages. The choice they have made certainly be speaks something more than mere unreasoning instinct, and does honour to their discernment."

To the following passage, we request particular attention.

"The nest of this bird is of singular construction, being formed of very small twigs, fastened together with a strong adhesive glue or gum, which is secreted by two glands, one on each side of the hind head, and mixes with the saliva. With this glue, which becomes hard as the twigs themselves, the whole nest is thickly besmeared. The nest itself is small and shallow, and attached by one side or edge to the wall, and is totally destitute of the soft lining with which the others are so plentifully supplied. The eggs are generally four, and white. They generally have two birds in the season. The young are fed at intervals during the greater part of the night, -a fact which I have had frequent opportunities of