House Sparrows furnish many examples of curious situations adopted for incubatory purposes. Not long ago a pair of these birds built their nest, and successfully hatched a brood, in the cartridge-box of a cannon which was fired twice daily in the Gun Park at Woolwich. It is a notable fact that in some parts of the country Sparrows build extensively in trees, whilst in others such a circumstance is unknown. Some ornithologists are of opinion that it is an hereditary habit, others supposing that it is resorted to for the sake of coolness in hot weather; but a reason I incline to is that in parts of the country where houses and out-buildings are made of stone the birds find ample accommodation in joints, crevices, and crannies where the mortar has been dislodged, and are therefore not driven to the necessity of adopting trees, like birds found in districts where the houses are made of bricks, consequently closer, and affording less opportunity for nest-building. This bird, besides its noted pugnacity, is an arrant rogue, and invariably takes advantage of the House Martin's labour. I have known a house with twenty nests all close together under its eaves, about half of which were occupied by Sparrows, which had, in some cases where the nests were new, been actually watched ejecting the eggs of the original owners. The Robin is noted for its caprice in the selection of a nesting site, and has been found hatching its eggs in nearly every conceivable situation, from the ordinary mossy bank to the pocket of a gardener's old coat which had been hanging undisturbed for several weeks in a tool-house. Old kettles, water-cans, inverted plant pots, &c., in buildings close to machinery in daily motion, and other equally curious places, are by no means rare occurrences. A case is recorded of a Robin's nest having been built in the hole made by a cannon-ball through the mizzen-mast against which Lord Nelson was standing when he received his death-wound on board the _Victory_. Swallows have also been known to adopt quite foreign situations for breeding purposes, such as holes in trees, and even openly on the branches. Cases are known of the Starling building its nest down holes in the earth, and also quite exposed in trees, similar to the nest of the Sparrow. It has also been found going shares with a Magpie. The Pied Wagtail occasionally chooses strange quarters, one case being on record of a pair building beneath a railway switch, over which trains passed nearly every hour in the day within a few inches of the nest. The roof of a house in Hull was once selected by two pairs of Rooks for nidification, and proved a successful choice, for they managed to build nests and rear their young.