108 



FIRST LESSONS IN POULTRY KEEPING. 



by an illustration from amateur photography with which many readers are somewhat familiar. 

 The photographer can purchase a little book containing carefully worked out tables which 

 enable him to determine in a moment just what time to give an exposure with the diaphragm 

 of any given dimensions and with any possible combination of light and surrounding objects. 

 By the use of such tables the photographer reinforces and regulates his judgment, and is enabled 

 to eliminate from his work much of the risk of spoiling plates or films and losing much desired 

 pictures. So in the development of artificial incubation we are evidently coming to a time 

 when the operator will be given more appliances to record conditions he has to reckon with, 

 just as the thermometer now records the temperature; and will be furnished tabulated instruc- 

 tions as to the adjustment of the machine to conditions. &', 



Meantime the amateur incubator operator need not be discouraged because in the operation 

 of incubators he must rely much on his own judgment. At this stage of affairs he may get as 

 good results as others by simply being sure he is on the safe side. 



I went one day to see the new incubator cellar on a large duck plant in this state. It was 





i r f 



One of Farrer Bros," 1 Brooder House?, W. Norwell, Mass. 



built something like that in the illustration, but with the walls high enough above ground to let 

 in full half windows on the sides, while the roof was high in the middle. As you entered the 

 door and looked about the effect was much like that of an empty church. In a church or any 

 other building for large gatherings the walls must be high that there may be in the room a 

 volume of air great enough to move and create the necessary ventilation without great change 

 of temperature. The builders of this incubator cellar had the same end in view. There was 

 room enough in the building for a cellar higher than usually used for incubators and for a very 

 large loft over it. There was so much room that my first question was as to whether they had 

 completed the building, or intended to make a loft. The reply was that the building was to be 

 used as it was ; that it had been planned to give abundance of air to the machines. I noticed no 

 odor from the lamps and machines in that cellar. I have gone into many incubator cellars in 

 which the odor wa^ very bad. In some of these this was because ventilation was defective 

 regardless of the number of machines in operation ; in others it was because entirely too many 

 incubators were in operation in the room. 



