Experimental Methods. 



"3 



humidities varying from the saturation point to practically nothing. 

 With the exception of the reduction of humidity in warm weather, 

 which the calcium chloride tank does not satisfactorily accomplish, 

 the plant has fulfilled all our requirements. The extreme range in 

 temperature during the day is usually 2° and very rarely over 4° 

 and the extreme range in relative humidity ranges between two 

 and ten per cent, of saturation. The carbon dioxide remains 

 usually below 8 parts per 10,000 when air is supplied and when 

 stagnant conditions are maintained it rises to between 30 and 90 

 parts depending on the number of occupants in the room and the 

 weather conditions outside which influence inevitable leakage. 



69 (1001) 



The experimental methods of the New York State Commission on 



Ventilation. 



By Frederic S. Lee. 



[From the New York State Commission on Ventilation.] 



Since December 8, 1913, the New York State Commission on 

 Ventilation has been conducting an extended series of experiments 

 on the physiological and psychological action of various atmos- 

 pheric conditions. For most of the tests human beings have served 

 as subjects; a few lines of observation have been carried out on 

 animals. The rate of the heart beat and the blood pressure have 

 been studied by the usual methods and have subsequently been 

 evaluated according to the Crampton, the Barach and other indices. 

 Bodily temperature has been measured chiefly by clinical ther- 

 mometers and at times by the constant temperature recorder of 

 Leeds and Northrup. This instrument consists of a self-balancing 

 Wheatstone bridge, is sensitive to one tenth of a degree, and makes 

 on paper a continuous record of rectal temperature. The appar- 

 atus proved very prone to get out of order and for this reason 

 could not be used as constantly as was desired. Muscular work 

 was performed by the lifting of dumb-bells to a given height, the 

 number of lifts being recorded by a telephone counter. For more 

 exact determinations of the amount of work performed a Krogh 

 bicycle ergometer was employed and proved very satisfactory. 



