252 FRIENDS WORTH KNOWING. 



further remarked that some of these martins' holes are 

 nearly as circular as if they had been planned out with a 

 pair of compasses, while others are more irregular in form ; 

 but this seems to depend more on the sand crumbling away 

 than upon any deficiency in its original workmanship. The 

 bird, in fact, always nses its own body to determine the 

 proportions of the gallery, the part from the thigh to the 

 head forming the radius of the circle. It does not trace 

 this out as we should do, by fixing a point for the centre 

 around wliich to draw the circumference ; on the contrarj^, 

 it perches on the circumference with its claws, and works 

 with its bill from the centre outward ; the bird conse- 

 quently assumes all positions while at work in the interior, 

 hanging from the roof of the gallery with its back down- 

 ward as often as standing on the floor. We have more 

 than once, indeed, seen a bank -martin wheeling slowly 

 round in this manner on the face of a sand-bank when it 

 was just breaking ground to begin its gallery. 



" This manner of working, however, from the circumfer- 

 ence to the centre unavoidably leads to irregularities in the 



direction Accordingly, all the galleries are found to 



be more or less tortuous to their termination, which is at 

 the depth of from two to tliree feet, w^here a bed of loose 

 hay and a few of the smaller breast-feathers of geese, ducks, 



