48 'AVIARIES, BIHD-ROOMS AXD CAGES. 



under the bottom window frame, as shown in 

 Fig. 27. 



For .ventilating 

 purposes coarse per- 

 forated zinc should 

 be used in preference 

 to wire netting, be- 

 cause by using this 

 one never lets a 

 draught into the 

 room, while at the 

 same time fresh air 

 is freely admitted. 

 Of course, in the 

 height of summer, 

 when all places are 

 stuffy and hot, the 

 extra air admitted by 

 the use of the wire 

 netting would be a 

 great consideration, 

 so that it is a good 

 plan to have two 

 frames made to fit 

 into the opening. 

 Fig. 27 Ventilation by means of an Upon one can be 

 ordinary Window. nailed the perforated 



zinc, and on the other the wire netting; these, being 

 interchangeable, can be used as required. 



THE HEATING PROBLEM. 



With the ventilation problem naturally follows the 

 question of heating. With a good supply of air in a 

 room-, heating will naturally increase in circulation, 

 and when we heat or attempt to heat a .bird-room we 

 must not on that account shut off the supply of the pure 

 element; on the other hand we must somewhat increase 

 it, especially if heating powers of a combustible nature 

 are used, because we are by this means burning the life- 

 giving oxygen from the air, and must therefore supply 

 it in greater quantities to make up the deficiency. 



