200 



THE HUMAN MOTOR 



Fio. 139. 



Respiratory Curves. 



With this increase of rhythm there is a corresponding increase 

 of the pulmonary ventilation, which tends to eliminate rapidly, 

 the carbonic gas, which is a poison to the neuro-muscular organs. 



If the work is very heavy, or takes place under bad conditions, 



CO 



CO 2 accumulates in the tissues ; hence the ratio ~=- 2 diminishes 



U 2 



and, the subject becomes breathless^ 1 ) Therefore anything that 

 impedes the respiration should be avoided in order that breath- 

 lessness shall not interfere with the work. 



The following table gives the respiration per hour during a 

 total of 45,000 kgm. of work done in five consecutive hours on 

 the bicycle dynamometer : ( 2 ) 



HOURLY FLOW OF THE RESPIRATION. 



It will be seen that the flow finds its level in the second hour 

 of working. Whilst in repose it is 500 litres on the average. The 

 production of 9,000 kilogrammetres of work per hour brings it to 

 1,100 litres. A large amount of work causes 1,500 to 2,000 litres 

 to pass through the lungs per hour. In order that such volumes 

 of air may be constantly pure, the workshops must be large and 

 thoroughly ventilated. 



From a practical point of view, the rhythm of the movements 

 must not be such as to produce breathlessness, a cause of prompt 



(*) F. Lagrange (Revue Scientifique, 1887, p. 718). 

 (*) Jules Amar, Le Rendement, p. 64. 



