196 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



APPARATUS FOR MAINTENANCE OF THERMAL CLIMATIC 



CONDITIONS 



By S. J. Hunter, Lawrence, Kans. 



[A summary of this paper appears in the discussion below. — Ed.]. 



President W. D. Hunter: Any discussion? 



Mr. T. J. Headlee: I am very much interested in this subject 

 and should be glad to have the speaker explain the following points: 

 1st, whether the temperature maintained is supposed to be a constant 

 one, or whether it is intended to show a diurnal variation; 2d, the 

 exact source, nature, measurement or control of the light; 3d, the 

 control of atmospheric moisture. 



Mr. S. J. Hunter: This temperature control apparatus (plates 5, 6) 

 is constructed to fulfil our specific requirements. I do not undertake 

 to say that it will fulfil hypothetical conditions arbitrarily imposed. 

 The chamber is 5'x 5'x 8', double glass lined on four sides. The 

 temperature is controlled by an ammonia compressor, while the 

 power is furnished by a f-H.P. D.C. motor. Sunlight can be admitted 

 from the south and west or excluded as desired, leaving dayhght 

 from the north. We can maintain constants or variables from 60" 

 above to 10° below zero F. Standard constant conditions are easier 

 to maintain than the establishment of given curves of variation. 

 Constants do not occur in nature; hence, for the present with these 

 we are not concerned. Standard weather guages keep the records. 

 The purpose of this aj^paratus is to interpret the influence of temper- 

 ature and moisture as natural climatic conditions on growth and 

 development. The climatic data is taken from our climatic records, 

 continuously observed since 1868. 



Mr. T. J. Headlee: How does the speaker plan to control or 

 determine the relative proportion of gases in the air? 



Mr. S. J. Hunter: Ventilation can readily be secured and normal 

 conditions of surrounding atmosphere maintained through ventilators 

 aided by electric fans. The moisture content can be controlled by 

 chloride of lime filtration. 



Mr. T. J. Headlee: In the study of the effects of temperature 

 and moisture on the rate of insect metabohsm I have not found it 

 possible to control the intensity of the light. The difference in the 

 results obtained from experiments conducted under the same temper- 

 ature and moisture and under practically the same food and gas 

 conditions at different times of the year are difficult to account for 

 so long as the intensity of the light is an unknown factor. In fact, 

 it is possible that the ascribing of a difference in response obtained 



