1^42 



The Cornell Reading-Courses 



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Diffusion. — By the diffusion method the fresh air enters the heater, is 

 warmed, passes into the upper part of the egg chamber, and is diffused 



through the pores of a diaphragm of 

 burlap or other materiaL It then 

 passes down over and around the eggs, 

 and out of the incubator through the 

 ventilators or the heater.^ (Fig- 52.) 

 Radiation. — By the radiation method 

 heat is supplied to the egg chamber by 

 direct radiation from a hot-air or a hot- 

 water tank or pipes. (Fig. 53.) 

 The contact method of supplying heat to eggs that are being incubated 

 is little used. Although this method approaches natural incubation most 

 nearly, it is the least successful. (Fig. 54.) 



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Fig. 53. — Radiation method. A , Metal 

 radiator; B, C, egg tray; D, ventilators 



QUALITY AND CAPACITY OF INCUBATORS 



Quality should be the first consideration. The main qualification of a 

 good incubator should be first-class material put together in such a way that 

 the process of incubation may be carried on successfully, conveniently, 

 and inexpensively. The value of an incubator should not be based on a 

 record hatch that was obtained when the incubator was operated by an 

 expert ; neither should an incubator be condemned because an inexperienced 

 operator fails at first to get good results. The best incubators for average 

 operators are those by which the problems of supplying heat, moisture, and 

 ventilation, are so simplified and controlled that good hatches may be 

 obtained in various localities and under varying atmospheric conditions. 



If enough chickens are to be hatched each season to make it advisable to 

 incubate by artificial means, a con- 

 siderable amount of time and extra 

 expense may be saved by installing 

 incubators of large capacity. Incu- 

 bators holding two hundred and fifty 

 to four hundred eggs are desirable. 

 The expense for oil and labor required 

 in operating large incubators is surpris- 

 ingly small in comparison with the 

 amount used in operating enough 60- 

 or loo-egg incubators to hold the same 

 number of eggs ; and the results usually obtained with the former are 

 enough better to warrant their use. The smaller the incubator, the more 



' Nearly every company manufacturing incubators has its own method of letting out of its incubator the 

 air that has been used. 





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Fig. 54. — Contact method. A heated 

 surface is brought in contact with the 

 eggs. A, Hot-air pipe; B, heated 

 surface; C, egg tray; D, ventilators 



