228 



PHYSIOL OGICA L PHYSICS. 



[Chap. XXI 



tube and the manometer to be placed in communi- 

 cation at pleasure. The short limb of the mano- 

 meter, as well as the intermediary tubing, was 

 filled with a concentrated solution of bicarbonate 

 of soda before the connection with the artery was 

 established. This was for the purpose of preventing 

 coagulation of the blood by contact with the tube, a 

 circumstance which would prevent a correct result. 

 In 1848 Ludwig adapted to the mercury a float which 

 passed up the tube, and, after issuing from the top, 



carried a horizontal arm with 

 a fine point, which, brought up 

 against the blackened surface of 

 a revolving cylinder, registered 

 in curve form the oscillation 

 of the mercury. To this form 

 the name of KYMOGRAPHION was 

 given by Volkmanii. Another 

 improvement consisted in so ar- 

 ranging the connection with the 

 vessel that the circulation should 

 not be arrested in it. This is 

 effected, not by simply tying 



.Scheme of Lud- ,, , , ' . .i/ i v 1 v 



wig's Kymographion. tne tulje mto tne VCSSel, but by 



One limb of the tube is repre- making a SlllD ill the side of the 

 sented tied in the vessel i L i , mi i 



c, and the mercury in that Vessel, aild UlSertlllg a 1-Sliapecl 

 limb is depressed to the i , ., mi i . i 



extent '. the mercury tube lllto it. llie horizontal pOl'- 



in the other limb being -.- n , i rr\ i i j i i 



raised a corresponding tlOll OI tlie 1 IS tied 111 tlie VCSSel, 

 amount db. /is the point i ji i , 



of the float s writing on aild the Vertical portion IS COll- 

 there volving cylinder c. , -,i ,\~ , 



nected with the manometer. 



Thus the horizontal part of the tube becomes part 

 of the vessel, from a part of the wall of which the 

 vertical portion springs, just as in the case of the 

 piezometers described on page 211. 



One great objection to the mercury manometer 

 yet remains, viz. that owing to the inertia of the 

 mercury it does not record the absolute movements of 



