BLOOD PRESSURE. 



243 



The other features consist of secondary oscillations, which 

 vary according to the tension of the arterial wall and the 

 inertia of the instrument. 



A hard pulse shows many of these, owing to the quick 

 elastic reactions which accompany the greater state of tension. 



A soft pulse, on the other hand, shows less height of curves, 

 less acuteness in the angles, and a less number of secondary 

 oscillations. 



Blood Pressure. Estimate this by means of the sphyg- 

 mometer (Hill & Barnard). 



See that the column of fluid stands at zero. To adjust 

 this, hold the instrument vertically, open the tap at the top, 

 and press the rubber ampulla gently upon the surface of a 

 table, supporting it with 

 both hands to control 

 your movement, and 

 closing the tap the 

 moment the fluid stands 

 at zero. 



(a) Artery. Press the 

 ampulla upon the radial 

 until the maximum pul- 

 sation of the column of 

 fluid is obtained. The 

 pressure will then be the 

 same inside and outside 

 the vessel, e.g., in the 

 sphygmometer, and its 

 magnitude is read off 



FlG. 48. Hill & Barnard's Sphygmometer. 



on the stem, which is graduated in terms of millimetres of 

 mercury. 



