294 THE OUTGO OF ENERGY 



Reverse the pole-changer, so that the anode 

 lies at the cross-section. Open and close the 

 galvanic current. 



Contraction will take place at closure only. 

 The electrode at the cross-section again refuses. 



2. Compensation 'Method. The electromotive 

 force of a current of injury may be expressed in 

 fractions of a Daniell cell, or any other constant 

 element, by bringing into the same circuit with the 

 current of injury, but in an 

 opposite direction, so much 

 of the current from the cell 

 as will exactly balance the 

 current of injury, i. e. so 

 much as will keep the menis- 

 cus of the electrometer from 

 moving in either a positive 

 or negative direction when 

 Fig. 47- connected with the circuit. 



Prepare a sartorius muscle. Connect a Daniell 

 cell with the and 10 metre posts of the rheo- 

 chord. Connect the capillary electrometer to a 

 closed short-circuiting key. From the post joined 

 to the capillary lead to the post of the rheo- 

 chord. Connect the remaining post of the key 

 to a non-polarizable electrode placed on the cross- 

 section of the muscle. Join the slider of the 

 rheochord to another non-polarizable electrode 



