BIRD HOUSES AND NATATORIUMS 231 



ing the inside diameter of nests six by six by six with 

 the entrance about two inches in diameter. 



Very attractive houses may be made from cheese 

 boxes, but are more trouble to construct, owing to the 

 difficulty of adjusting the partitions, but they well re- 

 pay the extra labor. For a five room bluebird or 

 martin house a single cheese box is used and the first 

 thing to do is to find a round piece of wood — a bar- 

 rel head is just right — ^for the top and bottom. Find 

 the exact center of these and of the cheese box and 

 with an inch and a quarter auger cut a hole through 

 all four pieces, having them exactly in line. These 

 are for the insertion of a piece of wood — a piece of 

 a curtain pole is just right — around which the box is 

 to be built. Pieces of wood as long as the distance 

 from the center hole to the edge of the box and as 

 wide as its depth are next fitted into the box and 

 nailed with thin brads to sides and bottom. Holes 

 are then cut with a very sharp bit near the bottom 

 of each compartment — ^two inches for martins, one 

 and three-fourths inches for fly catcher, one and one- 

 fourth inches for chickadees, one inch for wrens and 

 one and a half inches for Carolina wrens and tree 

 swallows. Under each opening place a perch as sug- 

 gested for the square boxes, and attach the top and 

 bottom to the box. To do this it will be necessary 

 to introduce some solid strips of wood, round or 

 square, inside the nests, as the thin wood of which 



