1 76 HOUSE-MARTINS. 



casion the bird not only clings with its claws, out 

 partly supports itself by strongly inclining its tail 

 against the wall, making that a fulcrum ; and, thus 

 steadied, it works and plasters the materials into 

 the face of the brick or stone. But, then, that this 

 work may not, while it is soft and green, pull itself 

 down by its own weight, the provident architect has 

 prudence and forbearance enough not to advance 

 her work too fast; but, by building only in the 

 morning, and by dedicating the rest of the day to 

 food and amusement, gives it sufficient time to dry 

 and harden. About half an inch seems to be suffi- 

 cient layer for a day. Thus, careful workmen, when 

 they build mud- walls (informed at first, perhaps, by 

 this little bird), raise but a moderate layer at a time, 

 and then desist, lest the work should become top- 

 heavy, and so be ruined by its own weight. By 

 this method, in about ten or twelve days, is formed 

 an hemispheric nest, with a small aperture towards 

 the top, strong, compact, and warm, and perfectly 

 fitted for all the purposes for which it was intended. 

 But, then, nothing is more common than for the 

 house-sparrow, as soon as the shell is finished, to 

 seize on it as its own, to eject the owner, and to line 

 it after its own manner. 



After so much labour is bestowed in erecting a 

 mansion, as nature seldom works in vain, martins 

 will breed on, for several years together, in the same 

 nest, where it happens to be well sheltered and 

 secure from the injuries of weather. The shell, or 

 crust, of the nest is a sort of rustic-work, full of 

 knobs and protuberances on the outside ; nor is the 

 inside of those that I have examined smoothed with 

 any exactness at all ; but is rendered soft and warm, 

 and fit for incubation, by a lining of small straws, 

 grasses, and feathers; and sometimes by a bed of 



