.Y OF MUSCLES AM> NKKYKS. 



184 



amount of weight required for this latter purpose affords 

 a measure of the force of attraction between the iron 

 and the magnet. 



In the present case a certain deflection in the multi- 

 plier results from the difference in tension at the feet 

 of the diverting arch. It is required to measure the 

 difference. If it is in any way possible to influence the 

 deflect ion of the multiplier in an opposite direct ion, and 

 exactly to such a decree that the multiplier no longer 

 indicates any deflection, then the two influences must 



I'K.. If,. Ml. AM KI.MKNT T.Y COMI'KXSATloX >! Till-: IHFKKia.Nt 1. (>K 



TENSION. 



he equal, and the one may serve as a measure for the 

 other. The experiment indicated in these instances 



i- called measurement by compensation. In order to 



applv it to the case in point, the action of one dif- 

 ference of tension is cancelled by that of another \\liich 

 ma\ lie altered at will. The rheochord. v, hich has al- 

 n .;idv lieen described, affords a COnvenienl means of 

 doiu<_;- I hi-. 



Let /.' /.'' (li^ r . -Hi) 1'c^i wire extended in a straight 



Line (the line of the rheo< hordj thro-.-^h \\hich a current is 



