144 BERTHA'S VISIT TO HER 



number of names given to this bird. It is very 

 like the chimney swallow, but it has no spots on 

 the tail, and its feet are differently formed, for 

 it has the power of turning the hind toe forwards, 

 in order to cling to a wall. This species are 

 chilly little creatures; when there is a cold wind 

 or rain, they press close to one another, and are 

 sometimes so benumbed as to be caught by the 

 hand. 



It is said that after they arrive here in April, 

 they play about for nearly a month before they 

 begin their nests. Sometimes they build in the 

 cliffs and rocks that hang over water; sometimes 

 against a perpendicular wall, without having any 

 support underneath the nest ; and they show 

 great sagacity in their mode of carrying on their 

 work. While laying the foundations, they not 

 only hold on by their claws, but they fix their 

 tail against some little projecting roughness in 

 the wall to serve as a kind of prop ; and then 

 with their bill they carefully cram mud and bits 

 of straw into the smallest chinks in the face of 

 the brick or stone ; and to give those materials 

 time to harden preparatory to a] fresh layer, 

 the prudent little mason only labours early in the 

 morning, so that his work dries sufficiently in 

 the course of the day. I have got up several 

 times at day-break to see how neatly he uses 

 his bill as a little trowel, while he carries the 

 mortar or clay in one of his feet. About half an 



