128 



INSTRUMENTS FOR INVESTIGATING THE PULSE. 



observations on the pulse-wave. He points out that the pulse occurs sooner in 

 arteries near the heart than in those placed further away from it, because the pulse 

 proceeding from the heart passes towards the periphery. Erasistratus placed a 

 cannula in the course of an artery, and he found that the pulse could still be felt 

 on the distal side of this point. Archigenes gave the name dicrotic pulse to a 

 condition which he had observed in febrile conditions. Galen (131 to 202 A.D.) 

 gave more exact details as to the relations of the dilatation and contraction of the 

 arteries during the movement of the pulse, and supplied much information on the 

 pulse-rhythm, and the influence of temperament, age, sex, period of the year, 

 climate, sleep and waking, cold and warm baths, on its rate and other qualities. 

 Cusanus (1565) was the first person to count the pulse-beats with the aid of a 

 watch. 



67. Instruments for Investigating the Pulse. 



The individual phases of the movement of the pulse could only be 

 accurately investigated by the application of instruments to the arteries. 



(1.) Poiseuille'S BOX Pulse-Measurer (1829). An artery (Fig. 43, a, a) is 

 exposed and placed in an oblong box (K, K) filled with an indifferent fluid. A 

 vertical tube with a scale attached communicates with the interior of the box. 

 The column of fluid undergoes a variation with every pulse-beat. 



K K 



Fig. 43. Fig. 44. 



Poiseuille's pulse-measurer a, a, exposed artery ; K, K, the Sphygmometer of 

 box consisting of two pieces ; ft, vertical tube, with scale He"risson and 



attached. Chelius. 



(2.) He'risson's Tubular Sphygmometer consisted of a glass-tube whose 



lower end was covered with an elastic membrane (Fig. 44). The tube was partly 

 filled with Hg. The membrane was placed over the position of a pulsating artery, 

 so that its beat caused a movement in the Hg. Chelius used a similar instrument, 



