THE MECHANICS OF THE CIRCULATION 



475 



mogram. Replace the valves in their normal position and wipe the 

 whole instrument dry. 



What are the characteristics of each sort of abnormal sphygmogram ? 

 Give the hydraulics of each case. Important. 



Expt. 28. Speed of the Pulse-wave in Man. (Apparatus: Two 

 thistle-tube sphygmographs, tubing, kymograph, tuning-fork, adjust- 

 able stand-rod, clamps, two chairs, rule, a tall, thin man with strong 

 pulse.) Let the subject sit sidewise in one chair at the table with his 

 bared right foot on its outer side in the other chair in front of him, and 

 his head resting on a folded towel on the table, left ear down. By means 

 of a stand-rod and clamps adjust the sphygmograph with the shorter 



FIG. 261 



Abnormal sphygmograms made on the artificial circulation-apparatus. The top line repre- 

 sents mitral stenosis; the line next below, mitral regurgitation; the next line, aortic stenosis; and 

 the bottom line, aortic regurgitation. To be read from left to right. The time-line is in seconds. 



tube to the subject's right carotid artery. By means of a table-clamp, etc., 

 adjust the transmitting tambour of the long-tubed sphygmograph to 

 the posterior tibial artery of the right foot at a point about half-way 

 between the middle of the inner malleolus and the middle of the bottom 

 of the heel, the foot being naked. Both sphygmographs must be firmly 

 held by clamps and the foot in a firm position. 



Adjust the recording tambours one close above the other on the kymo- 

 graph-drum with their writing-points exactly in a vertical line. Spin the 

 drum. Apply the 100 d. v. tuning-fork. Count the hundredths of a 

 second between the uprise of the two levers in several cases. This 

 obviously is the average time required for the pulse-wave to travel from 



