320 



CIRCULATORY SYSTEM. 



FIG. 166. Diagram of the recording mercurial manometer and the kymo- 

 graph ; the mercury is indicated in deep black : M, the manometer, connected by 

 the leaden pipe L with a glass cannula tied into the proximal stump of the left 

 common carotid artery of a dog ; A, the aorta ; C, the stop-cock, by opening which 

 the manometer may be made to communicate through RT, the rubber tube, with a 

 pressure-bottle of solution of sodium carbonate ; F, the float of ivory and hard 

 rubber; R, the light steel rod, kept perpendicular by B, the steel bearing; P, the 

 glass capillary pen charged with quickly drying ink ; T, a thread which is caused, 

 by the weight of a light ring of metal suspended from it, to press the pen obliquely 

 and gently against the paper with which is covered Z>, the brass "drum" of the 

 kymograph, which drum revolves in the direction of the arrow. The supports of 

 the manometer and the body and clock-work of the kymograph are omitted for the 

 sake of simplicity. The aorta and its branches are drawn disproportionately large 

 for the sake of clearness (Curtis). 



troduced into the femoral artery of a horse a brass-pipe whose 

 bore was one-sixth of an inch in diameter, to that, by means of 



