286 



THE HUMAN MOTOR 



Fw l&r. 



FIG. 185. Elliptical spring for receiving the pressure of the left hand 

 (B is seen in elevation and plan). The rubber bulbs, which are connected 



to receiving tympans of the Marey type, are placed at the points of appli- 

 cation of the efforts, which deform them through the medium of small 

 tangential metal discs. 



215. Evaluation of Efforts in Kilogrammes. To make use of 



any graph, such as Fig. 186, 

 for quantitive purposes, we 

 j? d must know its scale, i.e., to 



Fio. 18G. 



Graph of efforts. 



what weight a vertical dis- 

 tance of, say, 1 millimetre, 

 corresponds. 



In the case of the spring 

 hook, this calibration can be 



very easily effected by rigidly fixing the handle, hanging various 



standard weights thereto, and 



finding the corresponding 



heights of the ordinates from 



a graph such as fig. 187. 



This calibration should 

 always be carried out before 

 each series ol experiments. 



Consider, first of all, the 

 cabrouet the wheelbarrow, and 



10 



FIG 



75 



25 



Gauging of efforts. 



