OF SELBORNE. 26? 



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 pro- 

 vident architect has prudence and forbear- 

 ance 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 a sufficient 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 to- 

 wards 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-spar- 

 row, as soon as the shell is finished, to seize 



