THE MUSCLE-RHOMBUS. 



193 



the cross-sections, where the tension-curves, correspond- 

 ing with equal differences of tension, are nearer to- 

 gether toward the edge of the longitudinal section 

 than in the middle. If the feet of the diverting arch 

 are equidistant, the currents, both from the longitu- 

 dinal section and from the cross-sections, are therefore 

 stronger the nearer is the point under examination to 

 the limit between the longitudinal and cross-sections. 

 Fig. 51 shows this circumstance : A in the figure re- 

 presents the tensions on one of the longitudinal sections 



Fig. 51. Texsiox ox the longitudinal and cross sections of a 



muscle-prism. 



and on one of the cross-sections of the transverse section 

 represented in fig. 50 ; while at B the tension-curves in 

 a cross-section itself are represented. The latter, if the 

 muscle-prism is perfectly round, are concentiic circles. 

 In order to judge of the direction and strength of the 

 current resulting when a conducting arch is applied to 

 any two points of a muscle-prism, it is only necessary 

 to determine the difference of tensions at the feet of 

 the arch, and, in so doing, to notice that when positive 

 tension prevails at one of these points, negative tension 

 at the other, the current through the arch is always in 



