MEASUREMENT OF DIFFERENCES OF TENSION. 187 



Eeymond invented a * round compensator' (fig. 47), in 

 which the wire of the rheochord r r' is placed on the cir- 

 cumference of a circular disc of vulcanised india-rubber. 

 The beginning and the end of the wire are connected 



Fig. 48. Diagram of electric measurement by means of a kouni> 



compensator. 



with the clamps I and II ; from the beginning a wire 

 also passes to the clamp IV. The clamp III is con- 

 nected with the small reel 7% which is pressed by 



