470 



CHAMBERLAIN. 



were made at various hours between 8 a. m. and 4 p. m. Those observations 

 on white men which are included in the general averages were in many cases 

 taken after the soldier had been performing his usual military duties, such as 

 drill or fatigue. In a special group, not included in the general averages and 

 which will be described later, the blood-pressure readings and pulse counts were 

 made as soon as possible after vigorous exercise. In the case of the natives all 

 pressures were taken when the men had no exercise immediately preceeding the 

 observations. 



The observations on the 1909-Group continued for ten months, blood- 

 pressure readings being taken for each man on 4 occasions during that 

 period, the time between readings being about three months. In the 

 1910-Group, 5 blood-pressure observations were made on each individual, 

 1 at the commencement of a 13-month period, 1 at its end and the 3 

 others at quarterly intervals. In Tables II, III, IV, V, and XIII the 

 average readings are made up from the combined 4 or 5 quarterly ob- 

 servations taken on each man and so represent the mean annual hlood- 

 pressure. Therefore, it is obvious that the disturbing influence of such 

 factors as excitement, alcoholism, temporary indisposition, the ingestion 

 of food, or the taking of exercise, is reduced to a minumum and that the 

 average for each individual must represent very accurately his normal 

 blood-tension. 



STANDARD OF NORMAL BLOOD-PRESSURE IN TEMPERATE CLIMATES. 



The wide variations in normal blood-pressure which have been recorded 

 by different writers are probably due largely to the use of armlets varying 

 in width. Janeway states that in young adult males the systolic pres- 

 sure ranges from 100 to 130 millimeters of mercury when a 12-centi- 

 meter armlet is nsed. Gallawardin(4) considers the ordinary mean to lie 

 between 110 and 120 millimeters. A very valuable series of statistics 

 was published in 1910 by Woley. (5) He analyzed the blood-pressures 

 of 1,000 supposedly healthy individuals, using a 12.5-centimeter (5-inch) 

 cuff applied to the arm when the subject was in the sitting posture. He 

 found the average systolic pressure for all males to be 127.5 millimeters 

 and for all females 120 millimeters. Classifying his 1,000 cases accord- 

 ing to age he obtained the following results : 



Table I. — Woley's average systolic blood-piessures for 1,000 healthy persons in 

 the United States. {12. 5 -centimeter armlet.) 



Range of 

 age. 



Average 

 pressure. 



Range of 

 age. 



Average 

 pressure. 



Years. 

 15 to 30 

 30 to 40 



mm. 

 122 

 127 



Years. 

 40 to 50 

 50 to 60 



mm. 

 130 



132 



Faught considers the average normal systolic pressure at the age of 

 20 to be 120 millimeters. (9) Bachmann(7) examining healthy students 



