PRACTICAL PHYSIOLOGY 71 



struments for measuring or estimating velocity can 

 be successively connected by means of T-tubes. 



3. The pulse in the arteries. Feel the pulse in 

 the radial artery and determine (i) its rate, (2) its 

 quality, whether hard or soft, bounding, readily 

 compressible, etc. ; then apply a sphygmograph, 

 either Marey's original pattern or the modification 

 devised by Dudgeon. Use such a pressure upon 

 the spring of the sphygmograph as will allow the 

 variations in pressure within the artery to be most 

 manifest. The tracings are taken on slips of paper 

 smoked over a candle. Write on each slip the name 

 of the subject of the experiment and the pressure 

 which was employed ; varnish and preserve. 



4. Arterial pressure in man. The pressure of 

 the blood within the human arteries can be deter- 

 mined by applying over any artery, such as the 

 radial, the sphygmoscope of Hill or the sphygmo- 

 dynamometer of Oliver. Both these instruments 

 are adapted for showing the variations in pressure 

 which accompany the pulse, and it is found that 

 these fluctuations are best indicated when the pres- 

 sure of the instrument upon the artery is the same 

 as the average pressure of the blood within the 

 vessel. The point, therefore, around which the 

 largest fluctuations oscillate indicates the average 

 blood pressure. 



5. The respiratory movements in man. Ex- 

 amine the chest during quiet respiration, and notice 

 the parts in which most movement is evident ; the 

 same with forced respiration. Observe the altera- 

 tion in obliquity "and other changes in position of 



