A COMMERCIAL POINT OF VIEW. 19 



of sulphur. The roosting perches should be formed of 

 hot-water pipes, as they are of the utmost importance 

 to keep the poultry warm during the cold nights, and 

 cool during hot nights, arid which will induce a con- 

 tinuous laying of eggs during a time when they are 

 most scarce either for hatching or consumption. 



Most persons must have observed that even the 

 heaviest fowls will seek to perch nearest to the ceiling, 

 and that when roosting their feathers are ruffled or 

 open. This is easily explained by all persons con- 

 versant with the aerostatic laws ; namely, that heated 

 air being lighter than cold air it will ascend ; consequent- 

 ly the warmest place in a room will be nearest to the 

 ceiling ; therefore fowls open their feathers when roost- 

 ing to admit the warm, ascending air. Another impor- 

 tant point in the construction of this room is the creation 

 of a perfect ventilation without causing any draught. 

 Different gases, varying in their specific gravity, are 

 formed in this room, namely, carbonic acid, which is 

 a heavy gas and hangs near the floor, the ammoniacal 

 gas from the excrements of fowls, and carburetted hy- 

 drogen gas from the exhalation of the fowls, both of 

 which gases are light, and consequently rise to the ceil- 

 ing. It becomes, therefore, necessary to adopt a princi- 

 ple of ventilation by which both the heavy and light 

 gases can be got rid of without causing a draught, 

 which would be prejudicial to the health of the fowls. 

 This is accomplished by two pieces of perforated zinc, 

 one opposite to the other, near the floor, and the same 

 near the ceiling, and at least twelve inches above the 

 roosting perches. 



