"ON THE OUTWARD WALL" 



side. When it is placed in an angle formed by an overhang- 

 ing ledge or cornice, its shape is that of a quarter sphere ; 

 sometimes, however, it is built against a flat surface, and not 

 in a corner, in which case it is hemispherical in form. It is 

 clear that the safety of the whole structure depends upon 

 the firmness with which the foundations are fixed to the wall, 

 so the bird devotes a great deal of care to this portion of its 

 labours, often spending a week or more over laying down the 

 rim of mud which has to bear the weight of the whole 

 dwelling. By working only in the early morning, ii gives 

 each layer time to dry and harden ; but when the base is 

 quite firm and secure the work often proceeds more rapidly. 

 While laying the foundation, the bird not only clings to the 

 wall with its claws, but steadies and partly supports itself 

 with the help of its tail. The material is the same as that 

 used by the swallow and is carried in the same manner. 

 Neither the swallow nor the martin has a very capacious 

 mouth, so many hundreds of journeys have to be made in 

 order to cany enough mud to complete the nest. Any nest 

 that withstands the winter weather is at once reoccupied 

 when the birds return. The construction of an entirely new 

 nest is often delayed by many causes : the weather may be 

 either too wet or too dry ; in either case there is difficulty in 

 obtaining mud of the right consistency or in getting a solid 

 foundation. The martin often nests in far more exposed 

 situations than the swallow ; she 



Builds in the weather on the outward wall, 



and much labour may be lost thereby. Gilbert White 

 mentions such a case. " Birds in general," he writes, " are 

 wise in their choice of situation : but in this neighbourhood 

 every summer is seen a strong proof to the contrary at an 

 house without eaves in an exposed district, where some 



155 



