EXERCISE 23 (Continued) 



course of warm water or air, as the case may be, through the machine. Note 

 any ventilators or air filters. Note character of bottom solid, or slatted. 



Step 5. What is the method, if any, of supplying moisture in each 

 make of machine? 



Step 6. Study carefully the self-regulating device, note parts and their 

 names, and record simplicity and apparent efficiency. 



Step 7. Take a representative machine to pieces and study its internal 

 construction, as thickness and number of walls, insulating material used, with 

 location and amount of same. Note pipes for distributing heat. Replace 

 parts carefully and put machine again in working order. 



Step 8. From your experience as well as from this study, state which 

 machines you consider the most effective, and why. 



Leading Questions. 1. What materials do you find most commonly 

 used in incubator construction? Name other materials used. 



2. What is the limit of size in kerosene-heated machines? 



3. What is the effective capacity of a single tray? 



4. What special protection is provided to avoid fire in lamp-heated 

 machines? 



5. How many ways are there for controlling temperature automatically 

 on small lamp-heated machines? On mammoth machines? 



6. What is the general course of heat through an incubator? 



7. How is excessive circulation of air across the -eggs controlled? 



8. What different ways of saturating the air with moisture did you ob- 

 serve in the machines studied? 



9. What do you understand regarding the relative efficiency of hot air 

 and hot water machines? 



10. What are some of the most frequent causes of failure of an incubator 

 to operate properly? 



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