KYMOGRAPHS. 



299 



a recorder with a long rolled strip of paper can be employed 

 (Fig. 133). 



The moderate accurate methods of research have taught us 

 the differences in pressure that exist in the various parts of the 

 vascular system. However, direct measurement can only be ac- 



FTG. 138." 



LUDWIG'S KYMOGRAPH with continuous paper. The instrument consists of an iron 

 table, above which the recording surface is slowly drawn past the writing points from an 

 endless roll of paper on the left by the motion of the cylinder (c), and rolled up on a 

 spindle next the driving wheel on the right. The mercurial manometers (D) are fixed so 

 that the open ends come in front of the firm roller upon which the paper rests. The 

 wilting style can be seen rising from these tubes while the other limbs of the manome- 

 ters lead through the stop-cocks to the tubes which are in communication with the blood 

 vessels. The time is recorded by means of a pen attached to the electro-magnet (M), 

 which, by a "breaking" clock, is demagnetized every second. The moment at which a 

 stimulus is applied is marked by a key to which another pen is attached near the time 

 marker. 



complished in vessels of such a size as to admit a cannula, hence 

 the pressure in the capillaries, in the very minute arteries and 

 veins, can only indirectly be estimated. The pressure in all parts 

 of the vascular system is subject to frequent variation, to be pre- 

 sently mentioned, but this table may be useful in giving a gen- 



