350 THE OUTGO OF ENERGY 



will be very slight, and the greater portion of the 

 energy will be converted into tension and stored 

 in the spring. If the excursion of the spring be 

 recorded by a writing lever, the curve will be 

 practically a record of the course of transforma- 

 tion of energy into tension, and will be only to a 

 slight extent the record of a change in form. 



In order to determine the amount of energy 

 converted into tension in the isometric contrac- 

 tion, it is necessary to graduate the spring against 

 which the muscle pulls. 



Graduation of Isometric Spring. Attach the 

 large scale-pan to the strong spring of the appa- 

 ratus shown in Fig. 60. Place a long straw on 

 the end of the spring. Bring the writing point 

 against the smoked paper of a kymograph. Turn 

 the drum once round to record an abscissa. Re- 

 turn the drum to its former position, and place 

 80 grams in the scale-pan attached to the spring. 

 When the spring is stretched turn the drum once 

 round to record the bending under 100 grams' 

 weight. 1 Restore the drum to its former posi- 

 tion, add 100 grams, and make record of the 

 extension at 200 grams. Continue the record 

 up to 1000 grams. Preserve the curve for ref- 

 erence (page 363). 



1 The scale-pan weighs about 20 grams. 



