GLASS AND PNEUMATIC NOSEPIECES. 193 



GLASS AND PNEUMATIC NOSEPIECES WITH THE BENEDICT RESPIRATION 

 APPARATUS (SPIROMETER UNIT). 



Two types of nosepieces have been used in the comparison experi- 

 ments previously described: (1) the pneumatic nosepieces devised for 

 use with the Benedict respiration apparatus and (2) the round glass 

 nosepieces ordinarily used with the Tissot apparatus. The respiratory 

 exchange with these two types of nosepieces was therefore compared in 

 two experiments. The usual observations were made, the degree of 

 muscular repose being recorded by means of the bed-lever arrangement. 

 Both of the subjects were accustomed to the apparatus. 



SPiROKETER UNIT 

 NOSE BREATHING 



PER CENT OF VARIATION 



FIG. 51. Probability curves for the series of comparison experiments with nosepieces and mask 



(spirometer unit). 



The ordinates indicate the percentage of the total number of periods and the abscissae repre- 

 sent the percentage of variation from the average. 



STATISTICS OF EXPERIMENTS. 



J. K. M., July 12, 1912. Pneumatic nosepieces, 4 periods; glass nose- 

 pieces, 3 periods; preliminary period, 38 minutes; periods alternating after the 

 first two periods. Subject drowsy the latter part of the experiment and stated 

 that he preferred the glass nosepieces, as he could breathe more freely. Pulse- 

 rate varied somewhat widely in all of the periods, the range being from 6 to 

 8 beats per minute. Respiration fairly regular. Average barometric pres- 

 sure, 760.1 mm.; average temperature of air in apparatus, 23.5 C. 



P. F. J., July 13, 1912. Pneumatic nosepieces, 3 periods; glass nosepieces, 

 3 periods; periods alternating. Pulse-rate uniform, except in the first period 



