New York Agricultural Experiment Station. 139 



The whole piece of apparatus, indeed, seems to be very efficient, 

 and, considering its size and accuracy, moderately inexpensive. 



CONCLUSIONS. 



A piece of apparatus built recently for this Station is a combina- 

 tion of four incubators, of 7 cu. ft. capacity each, and a refrigerator 

 of 25 cu. ft. capacity. The incubators furnish temperatures between 

 18° and 50° C; while in the refrigerator a temperature of from 7° 

 to 10° is obtainable. 



The special features of this incubator are: electric heating, with 

 all the power utilized in heat production inside the chambers; cool- 

 ing by means of the drip-water from the refrigerator; and heat insu- 

 lation by walls of four-inch cork-board. 



This type of construction has the following advantages: 



1. It is efficient. Heat control is accurate, and great constancy 

 of temperature can be maintained. 



2. It is not expensive. Cork-board is relatively cheap, and 

 the cost of the heating apparatus is under $15. Total cost of 

 construction under $400. 



3. Cost of maintenance is low. The thorough insulation of the 

 walls and the utilization of all the current within the chambers 

 prevents loss of heat and therefore minimizes the consumption of 

 power. Total cost is below $40 per year. 



4. The risk of fire is negligible. Cork-board is not combustible, 

 the renewal of oxygen through the cracks of the doors is too slow 

 for active combustion, and the solder joints of the heating wires 

 would melt and break the circuit before reaching a dangerously 

 high temperature. 



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