“The swift, then, furnishes its own adhesive cement, but whence does it obtain the other materials it needs, such as tow, rags, straw, and feathers? Of course it is not so foolish as to go and pick them up from the ground, where it might find them as other birds do; for if it touched the ground it would certainly come to grief. Therefore it resorts to cunning. As it reaches us rather late in the season, it takes advantage of such holes as it finds already abandoned by the sparrows, and there it finds abundant materials which it uses in its own way by sticking them together with its glue. If the sparrows have not yet broken up housekeeping, it boldly invades their nests, steals bits of flock and tufts of hair, straw, and feathers, a little from one and a little from another, and makes with these its own nest in another hole in the same wall. The female lays from two to four eggs, pure white and rather elongated. Swifts seldom stay more than three months with us. Arriving after the swallows early in May, they leave at the end of July. “The white-breasted swift differs from the bird I have just described in being larger and having a white breast and stomach. It is found in the region of the Alps and of the Pyrenees and frequents the Mediterranean shores, especially where the waves beat against high, steep cliffs. Middle and northern Europe are not visited by this bird. Its flight is even swifter than that of its black cousin, and it flies habitually at a great height, descending only when bad weather threatens. It builds its nest at the summit of high, steep rocks, making it of straw and moss stuck together with the glue from its own throat. “The night-jar closely resembles the swift, having, like that bird, a short beak which is very broad at the base and opens very wide, while from the gullet comes a sticky saliva for holding fast any insects that are caught. Its size is about that of the thrush; its plumage is light, soft, and shaded with gray and brown; its eyes are large and prominent and very sensitive to light; the base of its beak bristles with long, stiff hairs; and its legs are short, but at the same time not ill adapted to walking. “As indicated by the sensitiveness of its eyes, which cannot endure the full light of day, and by the softness and lightness and gray color of its plumage, which resembles that of the hornless owl, the night-jar is a twilight bird: it is the swift of the evening, flying and hunting only when the sun is near setting. By the fading light of a summer evening it may be seen scanning the ground in low flight to and fro over its surface, after the manner of the swallow. It flies with mouth wide open, so that the air in striking the throat produces a low and continuous humming like that of a spinning-wheel.” “And is it from that humming sound that it gets its name of night-jar?” asked Jules.