222 The Natural History of Selborne 



true tone and texture after it has been so long benumbed by 

 the severities of winter. About the middle of May, if the 

 weather be fine, the martin begins to think in earnest of pro- 

 viding a mansion for its family. The crust or shell of this 

 nest seems to be formed of such dirt or loam as comes most 

 readily to hand, and is tempered and wrought together with 

 little bits of broken straws to render it tough and tenacious. 

 As this bird often builds against a perpendicular wall with- 

 out any projecting ledge under, it requires its utmost efforts 

 to get the first foundation firmly fixed, so that it may safely 

 carry the superstructure. On this occasion the bird not only 

 clings with its claws, but partly supports itself by strongly in- 

 clining 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 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 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. 1 



After so much labour is bestowed in erecting a mansion, as 

 nature seldom works in vain, martins will breed on for several 



1 In the case of some house-martins which had built under the eaves of 

 my own cottage, I removed no less than twelve successive nests of sparrows. 

 While each nest was being removed, the sparrows hopped about close by 

 with building materials in their mouths, looking exceedingly saucy, and 



