The Measurement of Arterial Pressure in Man. 519 



an external coat of muslin. The condom 

 thistle funnel ; the tube of each funnel 

 passes through a rubber cork. The corks 

 close the ends of the compression chamber. 



A pulsatile flow of water is maintained 

 through (A) the artery, (B) the tissue 

 schema. The water finally escapes through 

 a glass nozzle into a pail. The resistance 

 of the tissue schema is such as to give a 

 continuous flow from the nozzle, marked at 

 each systole by a slight pulsatile increase. 

 The pulsatile flow is secured in this wise. 



"Water flows through the tap through a 

 length of rubber tubing to the schema. 

 Close to the tap a mercury valve is inserted 

 so that the pressure in the tube is kept con- 

 stant. The rubber tube is pulsed rhythmi- 

 cally between two wooden discs (cotton 

 reels), one of which is fixed to the support, 

 and the other to the piston rod itself, of 

 Brodie's respiration pump. At each stroke 

 of the pump the tube is compressed and the 

 flow interrupted. The rate of the pulse can 

 be varied. T-pieces are inserted in the 

 schema so that the pulse and pressure can 

 be recorded in turn from (i) one compres- 

 sion chamber or both chambers, (ii) the 

 tube connecting artery and tissue schema, 

 (iii) the outflow nozzle. An alternative 

 pathway is arranged in the compression 

 chamber which contains the artery, so that 

 the flow can be directed either through the 

 artery or through a piece of rubber tube, 

 which acts as a rigid tube. Or two pieces 

 of artery, one acting as artery and the other 

 as vein, can be placed in this compression 

 chamber ; the flow is then made to pass 

 through (1) the artery, (2) the tissue schema, 

 (3) the vein, and so to the outlet nozzle. 

 Or the flow can be made to go through 



is tied at either end on to a 



