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HANDBOOK OF PHYSIOLOGY. 



invented an instrument called a sphygmometer, in which these defects of the 

 sphygmograph are corrected. 



Fig. 182. Dudgeon's Sphygrnograph. 



The principle of the sphygmometer of Roy and Adami is shown in the dia- 

 gram (fig. 183). 



The apparatus consists of a box (a) which is moulded to fit over the end of 

 the radius so as to bridge over the radial artery. Within this is a flexible bag 

 (b) filled with water, and connected by a T tube with a rubber bag (h) and 



To manometer. 



Fig. 183. Diagrammatic sectional representation of the sphygmometer (Roy and Adami). a, 

 Box in which the portion of the artery is inclosed: 6, thm-walled india-rubber bag filled with water, 

 and communicating through tap, c, with manometer and thick-walled rubber bag, h\ d, piston con- 

 nected by rod, e with recording lever, /; g. spiral spring attached to axis of lever, and by which 

 the pressure in 6, against the piston, d, is counterbalanced; k, skin and subcutaneous tissue- m end 

 of radius seen in section; n, radial artery seen in section. 



