SYSTOLIC BLOOD-PRESSURE AND THE PULSE RATE. 469 



The blood-pressui-e work on white men was done at 7 points, Camp Stotsenburg, 

 Fort William MeKinley, Camp Jossman, Warwick Barracks, Torrey Barracks, 

 Pettit Barracks, and Augur Barracks. Part of the natives were examined at 

 these places, but the majority were tested at Camp Gregg, Corregidor Island, 

 and in Manila. All of the 10 places above mentioned are located on or close to 

 the coast-line and but little above sea level with the exceptions of Camp Stot- 

 senburg and Camp Gregg which are in the interior at altitudes not exceeding 

 200 meters. Tlie climate at these two last posts does not differ materially from 

 that at the other stations nearer the sea. 



BLOOD-PRESSURE APPARATUS AND METHOD OF USE. 



The instniment used for all of the tests was the portable form of 

 Doctor Cook's modificatioii of the Eiva-Rocci apparatus. The original 

 instrument devised by Doctor Cook had a 4.5-centimeter annlet, which 

 width, according to the experience of most observers, gives readings that 

 are too high. ( 3 ) The results are more markedly exaggerated, above what 

 they should be, when the pressure is considerably above normal or when 

 the circumference of the arm is great. Brlanger, v. Eecklinghausen, 

 G-allavardin, and Janeway all advocate a 12-centimeter cuff. The in- 

 struments with which our routine observations were made had an armlet 

 8 centimeters in width. In order to reduce the readings made with this 

 8-centimeter cuff to the basis of a broad armlet we made a series of 140 

 comparative observations on 60 white men and 388 observations on 120 

 Filipinos, using with Doctor Cook's apparatus one cuff of a width of 8 

 centimeters and another of 12.5 centimeters (5 inches). "We found that 

 with the 12.5-centimeter cuff the recorded pressure on the average was 

 lower by 8 millimeters for white men, and by 6 millimeters for Fili- 

 pinos, than was the case when the 8-centimeter armlet was employed. 

 The difference between the results in the two races probably was due to 

 an average smaller circumference for the native arms. In the tables 

 which follow the average readings have all been reduced to the basis of 

 a 12.5-centimeter armlet by deducting 8 millimeters for the whites, and 

 6 millimeters for the natives, from the averages of the original observa- 

 tions made with the 8-centimeter armlet. 



It may be argued that a constant deduction of 8 millimeters would give 

 inaccurate individual results for the very higJi and for the very low pressures. 

 Even if this be so it would not affect the average figures given in our tables 

 since they are in all cases the average of individual readings on great numbers of 

 men and the 8- or 6-millimeter deduction is the mean difference in a large 

 series of men of the same race, occupation, and physical type. 



We applied the cuff to the upper arm and for determining the pressure used as 

 a criterion the return of the pulse wave in the radial artery. Nearly all of 

 our observations were taken with the soldier in the sitting posture. For some 

 individuals the readings were made when the men were reclining, but the 

 numbers so recorded are so small in comparison with the total number of men 

 observed that it would not materially affect the averages even if it be granted 

 that there is a constant slight difference between the readings in the two postures. 

 Erlanger and Hooker found the pressures about the same sittiilg or lying and 

 Janeway considers the postural variations to be insignificant. (3) Our observations 



