THE CIRCULATION. 



305 



COPYRIGHT '1906. BY SCHNEIDER BROS,, W.\ 



Fig. 102 a. Erlangers apparatus for Determination of the Blood- 

 pressure in Man. 



The apparatus is provided with a pneumatic cuff, which consists of an inside 

 rubber bag and an outside leather band. The whole cuff can be buckled around 

 the arm above the elbow. The air cavity within the rubber bag of the cuff 

 communicates through a thick-walled rubber tube and a four-way connection, 

 *=Y= with the three other essential parts of the apparatus, namely: (1) 



downward, with the valved bulb, by means of which air can be forced into 

 the cuff and can thus be made to compress the arm; (2) to the left, with the 

 mercury manometer, from which the amount of pressure applied to the arm 

 can be read directly in mm of Hg; and (3) upward, with the distensible bag 

 inside the glass chamber. This bag, last mentioned, responds to fluctuations 

 of pressure inside the rubber bag of the arm, which are due to vibrations of 

 the arterial wall, and the tambour a,t the top records such vibrations on the 

 drum. (TIGERSTEDT. ) 



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