THE MYOGRAPH. 53 



Fig. 17 represents it in the form given to it by du Bois- 

 Reymond. The clockwork enclosed in the case c sets 

 the cylinder A in rotation. A heavy disc B is fastened 

 on to the axis of the cylinder, on the lower surface of 

 which are certain brass wings arranged vertically and 

 immersed in oil. This oil is contained in the cylin- 

 drical vessel B'. By raising or lowering this vessel the 

 amount of resistance offered to the rotatory motion 

 may be graduated. This, together with the great 

 weight of the heavy plate B, causes the rate of rotation 

 of the cylinder A to increase but very slowly. As 

 soon as a proper speed has been attained, the muscle 

 is irritated ; and this, on contracting, raises the lever c 

 -so that the point e fastened to the latter traces a curve 

 on the cylinder. 



To carry out the experiment, the muscle is fastened 

 in a vice within the glass case, so as to prevent its 

 drying up, and is then connected with the lever c ; the 

 cylinder A is covered with a coating of soot, and is then 

 firmly fastened on its axis ; the pointed indicator is 

 brought into contact with the cylinder by means of 

 the thread /. When this cylinder is slowly turned 

 round by the hand, a horizontal line is inscribed on it 

 by the indicator, and this represents the natural length 

 of the quiescent muscle. On the circumference of 

 the disc B is a projection called the ' nose.' When 

 the disc together with the cylinder connected with it 

 are in a certain position, this nose touches the bent 

 bayonet-shaped angled lever I. When the latter is 

 turned aside it raises the lever h by means of the arm 

 i, thus breaking the contact of a current between the 

 lever and the small column standing in front of it. The 

 current of an electric chain is conducted through this 



