PHYSIOLOGY OF MOUTH-BREATHING APPLIANCES. 



191 



TABLE 51. Respiration-rate and rate of pulmonary ventilation (unreduced) in grade-walking experiments without 

 food, for studying effect of long and short duration of preliminary mouthpiece breathing. Subject, E. D. B., 

 SO per cent grade, at approximately 50 meters. (Values per minute.) Continued. 



all of the periods for each method of test on these 4 days, we find the 

 average reduced ventilation for the periods with long preliminary mouth- 

 piece breathing to be 45.8 liters and that for the periods with short pre- 

 liminary breathing to be 46.7 liters, with a difference of 0.9 liter or 

 1.97 per cent. (See table 16, p. 78). 



At first sight this relatively small difference appears to be a real effect, 

 ascribable to the short use of the mouthpiece. It is important to bear 

 in mind, however, that, as previously pointed out, the actual amount of 

 work performed in the two series was usually somewhat greater in the 

 second set of tests, this difference being not far from 1 per cent. Allow- 



