The penguins, like others of the diving sea-birds—our own guillemots and razor-bills, for instance—make no nests. Birds, however, taken as a class, are remarkable, as we all know, for the wonderful structures which they build, to lay and incubate their eggs in, and sometimes, as we shall shortly see, for other purposes as well. Chief, perhaps, amongst these wonderful builders come the weaver-birds, and especially that species which is named, _par excellence_, the sociable weaver-bird or grosbeak—for most of them are sociable in a greater or less degree. Though not more than about five inches long and of a plain appearance, these little birds, by uniting together, make, perhaps, the largest nest or structure that any bird makes, it being large enough to conceal four or five men from view, if they should get behind it. It is built, however, in a tree, and entirely of a very long, tough, and wiry kind of grass, called Bushman’s or Booschmannie grass, because it is plentiful where the Bushmen used to live—for the grass has outlived the Bushman. This grass the birds pull out of the ground, and when they have got a good bunch of it they fly to the tree they have chosen—which is often the pretty mimosa, or _kameel-dorn_ of the Boers—and lay it across a properly shaped branch, so that it hangs down upon either side. Then they plait and weave each row of ends together, and by constantly bringing more grass and continuing the process, pushing it out, as they go, so as to make it bulge, gradually, on each side of the branch, they make, at last, a hollow, thatched structure, narrow at the top, where it is supported by the branch, but getting wider as it descends, like the thatched roof of a cottage, which, indeed, it much resembles. It is higher, however, in proportion to its length, and so has roughly the shape of a beehive or diving-bell; or, again, it may be widened out at the top and made more rounded, so as to resemble the head of a gigantic mushroom. The structure is, of course, continuous all round, the two rows of hanging grass-stems having been woven together by the birds, at either end. Inside this hollow dome, or roof, the actual nests are now placed, each pair of birds building a separate one, though as they are all woven together, the whole of them, with the covering thatch, has the appearance of one structure when finished. The nests descend within the roof, to the same depth, so that the central hollow becomes filled up with a mass of material, within which, however, are a great number of smaller hollows—each one the nest of a pair of weaver-birds—like the cells of a honeycomb, but with wider spaces between each. A sort of thatched honeycomb, indeed—though without the honey—is what the completed structure may most be said to resemble, but really to complete it, takes many years; for it is not in one season, nor two, that the whole of the roof, or dome, is filled up. Indeed, when