"As the nest increases in size, it is obvious that the cavity in which it is placed must be proportionably enlarged; accordingly, each wasp, as it emerges from the aperture, may be observed to bring out with it a small lump of earth which it has scraped from the walls of the chamber, care being taken to keep a clear space of about a quarter of an inch between the covering of the nest, and the walls of the chamber. About the same space also occurs between the combs, which are placed horizontally, with the mouth of the cells downwards; supporting columns or pillars being constructed at regular intervals so as to keep them at a proper distance apart, thus allowing the insects room to pass between them for the purpose of feeding the grubs. Supporting columns or pillars are also placed between the roof of the chamber and the crown of the nest, connecting the one with the other; and these supports are constantly strengthened as the increasing weight of the nest renders such a precaution necessary. "The material of which the wasps' nests are composed is a sort of paper manufactured chiefly from wood by the insects themselves; one species using sound wood for the purpose, another that which has become decayed. This they scrape by means of their jaws from posts, rails, gates, hurdles, &c., in which act it becomes mixed with some peculiar fluid with which they are provided; it then possesses nearly the same properties as the pulp from which paper is made, but is of firmer consistence. This is gathered in a small lump under the chest, to which it adheres, and in that way is carried to the nest. "The operators having, after the exhibition of a considerable amount of fickleness in the choice, fixed upon a suitable place for commencing, or recommencing operations--for these remarks have reference to a nest already somewhat advanced in the building--place themselves along the edge of a yet unfinished piece, then walking slowly backward, spread the material as they go, along this edge, where it forms a thick streak; they then go forward to the point at which they began to spread the composition, again marching slowly backward, press this streak between their jaws, which acts as a pair of pincers, thus thinning it out throughout its whole length. They then go forward a second time, pressing it still thinner, and then a third, and so on, until they have rendered it sufficiently thin. Before this is accomplished, the operators have generally to go five or six times over their work. They do not return to the same spot with their next burden, but seek a fresh one, and thus allow the work they recently executed to become dry and firm, previous to making further additions to it. Possibly the material first 'used up' was from wood of a dark colour; the next may be from light-coloured wood, and the next from that of an intermediate colour; and this it is which gives so much beauty to the coverings of the nests of these insects.