Pulse and Respiration. 93 



arrangement, was able to secure graphic records of the pulse from the 

 carotid of subjects working vigorously on a bicycle ergometer. The 

 curves could be read for the duration of individual pulse cycles. To 

 minimize the disturbances from movements of the head and neck it was 

 usually necessary for the subject to rest the forehead and shoulders 

 against padded supports. The periods of work varied from one minute 

 to one hour and a quarter. 



Among later researches which have employed sphygmographic tech- 

 nique, those of Aulo 1 may be mentioned. Radial pulse was taken from 

 the right arm with an arrangement similar to that described by Tiger- 

 stedt 2 and used later by Dodge and Benedict 3 for their "association 

 pulse." The subject reclined in an easy chair or on a bed and, when 

 told, actively produced tension in all the bodily muscles, excepting that 

 the right arm was kept as relaxed and quiet as possible, as this was 

 essential for legible records. No periods of activity of less than a 

 minute are reported. 



Fortunately, with much less limitation of the subject, electro-cardio- 

 grams giving a photographic record for accurate determination of 

 heart rate can be taken under conditions of physical activity, and there 

 are no great complications caused by the vibration of the apparatus 

 or the movements of the subject. Miss Buchanan 4 took continuous 

 electro-cardiograms showing the pulse rate during moments of change 

 from rest to muscular tension. The subject sat with one hand and one 

 foot in vessels of salt solution connected with the terminals of a capil- 

 lary electrometer. Upon hearing a given signal he clenched the fist 

 that was free or gripped a hand dynamometer. The pulse-cycles were 

 measured individually in hundredths of a second and an account was 

 taken of the relation of the signal to the systole. Later the same 

 author (Buchanan) 5 took electro-cardiograms from a subject who was 

 riding on a stationary tricycle. No details of the application of the 

 leading-off electrodes are given. Benedict and Murschhauser 6 report : 

 "By using body-leads and the Bock-Thoma oscillograph or the Ein- 

 thoven string galvanometer, we were able to secure graphic records of 

 the pulse rate of the subject while he was walking upon the treadmill." 

 The treadmill was operated by a built-in 220 v., d. c. motor. As would 

 naturally be expected with so sensitive an instrument as the string 

 galvanometer, much difficulty was experienced from leakage currents 

 and static charges which found their way into the galvanometer cir- 

 cuit. After a special metallic brush, which was earthed, was arranged 



1 Aulo, Skand. Archiv f. Physiol., 1909, 21, p. 146; 1911, 25, p. 347. 



2 Tigerstedt, Hygiea, Festband, 1908. 



3 Dodge and Benedict's report, p. 192. 



4 Buchanan, Trans. Oxford Univ. Junior Scientific Club, n.s., No. 34, 1909, p. 351, reprintedin 

 The Smithsonian Report for 1910, pp. 487-505; Science Progress No. 17, July 1910, p. 60. 



6 Reported by Krogh and Lindhard, Journ. Physiol., 1913, 47 (see p. 117). 

 6 Benedict and Murschhauser, Energy Transformations during Horizontal Walking, Carnegie 

 Inst. Wash. Pub. No. 231, 1915, p. 31. 



