114 



306 J- A. MACWILLIAM 



observations by Ettinger, Goodman and Howell (57), (130) Warfield 

 and others. The characters of the sounds in different conditions are 

 so varied and striking that useful information as to circulatory states 

 may very possibly be derived from them when they are better under- 

 stood. 



It need hardly be emphasised that the Hg manometer is the reliable 

 means of measuring pressures; it is only when frequently checked 

 against this instrument that other forms (aneroids, etc.) can be taken 

 as giving valid evidence. In regard to diastolic pressure it may be 

 noted that the reading taken when the armlet pressure is being raised 

 is often appreciably lower (5 mm., etc.) than when taken during de- 

 flation; in some subjects the difference shows more than in others. 

 With reference to the systolic index the difference in the readings by 

 the auscultatory method and those by the tactile method have been 

 estimated at 5-14 mm. The experience of the present writer agrees 

 with the lower values, usually only a few millimeters. 



Blood pressures in young adults. In 1914 Melvin and Murray (97) 

 established by accurate methods normal values of both systolic and 

 diastolic pressures in healthy young male adults (sitting posture), 

 59 medical students, average age 20-9. As regards systolic pressure 

 only three were up to 130 mm. (viz., 130, 134 and 135) while five were 

 slightly below 100 mm., the average came out at 112 mm. Of the 

 diastolic pressures 28 were at 60 to 70 mm., 19 at 70 to 80 mm. and 12 

 at 50 to 60 mm. The pulse pressures gave an average value of 46 mm. 

 Subsequent observations on very large numbers of subjects by various 

 observers in different parts of the world have given S, and D. values 

 higher as a rule and sometimes with wider ranges of variation. Bear- 

 ing on this difference the observations of Alvarez (4) and of Burlage 

 (23) (to be stated presently) as to a lowering of pressure in the early 

 years of adult life are suggestive, as they include the ages dealt with 

 by Melvin and Murray. Sorapure (117) examining 769 British soldiers 

 also found a systolic maximum at 19 to 22 years followed by a slight fall, 

 as Stocks and Karn (121) did after a systolic maximum at 19 to 20. 

 It may be remarked that while large numbers are of course necessary 

 for statistical purpose, classification, etc., reliance on pressure measure- 

 ment on a single occasion is apt to introduce sources of error, in view of 

 the universally recognised tendency of single examinations to give 

 results disturbed by temporary causes, nervous excitement, etc. More 

 precise results, as regards the real pressure levels in individuals are 

 obtainable by a more intensive study of smaller numbers, by repeated 

 examinations under carefully ascertained and controlled conditions. 



