202 



THE HUMAN MOTOR 



would be measured. If a little rubber bulb is attached to the 

 pulse and compressed until the pressure of the pulse is balanced, 

 a manometer attached to the bulb will indicate the amount of the 

 arterial pressure. This arrangement constitutes Potain's sphygmo- 

 manometer. 



Pachon's oscillometer achieves the same result with more pre- 

 cision (see Technics, 248). 



For man in repose the following results have been found : 



The relation between the durations of the diastole and the 

 systole is : 



I : i = 3 approximately. 



The arterial pressure increases with age. It is 13 to 14 centi- 

 metres of mercury between 10 and 20 years, 17 to 19 centimetres 

 between 20 and 40 years, and it exceeds 20 centimetres after 

 50 (Potain) ; the systolic pressure is taken in these measure- 

 ments, the diastolic pressure being smaller. 



When a man performs work, the rhythm of the pulsations 

 increases to 100 and 120 per minute, and attains a steady value 

 if the work is normal and regular. This is 112 to 114 for work 

 amounting to 200,000 to 250,000 kilogrammetres in eight hours, f 1 ) 

 According to Otto Weiss ( 2 ) the extreme limit is 167. In this 

 activity the organism finds the condition of its resistance to 

 fatigue and the blood circulates oftener, so that, in unit time, 

 5 or 6 times more blood passes through the same organ. ( 3 ) The 

 following observations on the rhythm of the pulse are of 

 interest. ( 4 ) A subject covered 38 metres on the level at in- 

 creasing speeds ; his pulse, which was 75, becomes successively : 



85 



88 



84 

 increasing by 



9 10 13 



The duration of the walk was : 



30 27 26 



90 



90 



15 and 15 



19 



18 seconds. 



i.e. inversely proportional to the increases of the rhythm. 



(^'Atwater and Benedict (Bulletin, No. 136, p. 357, table 127). 



( 2 ) Otto Weiss (Pfluger's Archiv., vol. cxxiii., p. 341, 1908.) 



( 3 ) Chauveau and Kaufmann (Comptes Rendus Sc., 1886 and 1887). 



( 4 ) J. Amar, (unpublished observations). 



