48 

 be understood clearly that by inclining the box backwards — 

 that is to say, in a direction opposite to the ope ling — the direction of 

 the slope of the opening is neutralized, and rain can penetrate, 

 {See p. 32.) They must be so fastened that they cannot shake, as 

 otherwise the birds will not readily settle in them. The best means 



of fastening them is with the screw-nails (p. 38), and the easiest manner of 

 doing this, especially with the bigger and heavier ones is as follows : A 

 screw-nail must be knocked in at the chosen spot, just so far that its 

 head projects over the batten of the box, which is to be hung up — the 

 screw-nail must therefore project more than | inch out of the tree ; the 

 box must then be hung up on it (see p. 36), and the screw-nail finally 

 hammered in. 



