28 i EXPERIMENTAL INVESTIGATION OF THE ACTION OF MEDICINES. 



tinuous roll of paper from a bobbin, so that a tracing may be 

 taken uninterruptedly for an hour or two without renewing the 

 paper. In order to avoid the inconveniences of the mercurial 

 manometer, Tick has constructed one (Fig. 134) in vhich ihe 

 pressure is not measured by the movements of a column of 

 mercury, but by those of a bent hollow tube (a) fixed at one 

 end and free at the other. The tube is filled v/itli alcohol, and 



Fig. 134. 



rick's spring kjmograpliiou. a is u flat tube of German silver, fixed at one- 

 end B to a piece of board D. The other end c is freely movable, e is a tube 

 connecting a with the artery, f is a lever made of reed, connected to c. G is 

 the writing point, moved up and down by f, and kept perpendicular by auotiier 

 short lever altove. The tube A is filled with alcohol, and the tube E witli a soda 

 solution, and B is then connected with the artery. Whenever the pressure rises, 

 the tube A tends to straighten itself, but it is firmly fixed at the end B, and so- 

 the end c alone moves upwards, and pushes up the lever f and the writing- 

 point G. Whenever the pressure relaxes, the tube bends back again to its* 

 original shape, and the point G consequently again descends. The tracing is 

 taken by allowing G to rest against a revolving cylinder, covered with a piece of 

 p jper, whicli has been smoked either over a gas flame or a parafRn lamp. 



its fixed end connected with an arter}'. At every rise of 

 pressure this tube tends to straighten itself, and this motion of 

 the free end is communicated by it to a lever (f) and writing- 

 point (g), which records it on a smoked cylinder. 



The advantage of this form of kymographion is that it gives 



