February, '15] DEAN AND NABOURS: AIR CONDITIONING APPARATUS 111 



a change in the air pressure on the diaphragm steam valve, causing 

 the valve to partially open or close, thereby controlling the tempera- 

 ture of the heating chamber. 



The breeding chamber (Plate 2) consists of a double glass-walled 

 room, six feet wide, eight feet long, and seven feet high, with a small 

 entering vestibule. A complete change or displacement of the air in the 

 breeding chamber is produced every minute, the air flowing out at the 

 bottom of the chamber and entering the spraying chamber by means 

 of a large air duct shown at X. The outside air may also be brought 

 in by means of a large air duct w^hich comes in from the outside and 

 enters the same chamber as the air duct coming from the breeding 

 chamber. 



We gratefully acknowledge complete support for this undertaking 

 from Director W. M. Jardine. We are under special obligations to 

 Mr. A. W. Bellomy, assistant in genetics, for much of the work and the 

 whole of the supervision of the installment of the apparatus. We also 

 desire to express our appreciation of the invaluable services of Prof. 

 A. A. Potter and members of his staff in the Engineering Division 

 and of Mr. A. E. Stacey, of Chicago, engineer for the Company. 



Mr. T. J. Headlee: Thinking that the members of this Associa- 

 tion might be interested in a less expensive apparatus intended to 

 control temperature and moisture, I will venture to describe one which 

 I have recently devised. It consists of two small heating chambers 

 under absolute control. The Freas Electric Incubators ..ill serve 

 well or a cheaper form can be made. Within each of the two cham- 

 bers is placed an air-tight glass receptacle. By means of properly 

 insulated tubes the two air-tight chambers are connected. By means 

 of a faucet pump air from outside the building is sucked through the 

 two chambers. In passing through the first incubator the air is heated 

 to a given temperature and saturated with moisture by passing it 

 through a series of waterfilled chambers. On entering the second 

 chamber the air is heated to the temperature desired for the insect 

 and given the proper degree of relative humidity. By raising or 

 lowering the temperature of saturation, within reasonable limits, 

 any relative humidity can be created and maintained. In course of 

 rigid tests recently completed, two degrees of humidity were main- 

 tained for one week each. In an apparatus such as this the size did 

 not permit the use of a thermo-hygrograph and it was necessary to 

 resort to a modified form of the dew-point apparatus. If care be 

 used in purchasing the chambers, it is possible to secure chambers at 

 $100 to $125 a pair. No doubt further mechanical improvement 



