171 PHYSIOLOGY OF Ml'SCLKS AND NKKVKS. 



in-t.-ad of the-e two \\ir.-s ;i number of separate wires 

 are u-ed. then tin- same thin^ happen- : and if the wires 

 are w.-lded together i lit . . a cm 1 1 n i. >n conducting bodv, 

 this does not esseni ially alter the t-onditions of the fall, 

 80 that we may imagine the whole liodv to consist of 

 these separate -wires, in each of which a definite fall, 

 the steepness of which depends on the length of the 

 particular wire, prevails. Tlic.se wires are, however, 

 merely paths alon<.- which the electric currents pass, 

 and of which we have already spoken. In tin- case 

 of these paths also definite falls mii.-t prevail, and these 

 must be more steep in proportion as the points at 

 which the elect ric current s enter and make their exit 

 are nearer together. 



9. Let us return to the case of a simple wire 

 through which a current passes. On uniting two 

 points in this with two electrometers these exhil.it 

 varying tensions, and the difference is greater the fur- 

 ther the two points are separated" from each other. If 

 the points are then connected by a bent wire, it is 

 evident that the different tensions at the points of 

 contact nuist effect a disturbance in the natural elec- 

 tricity within the applied wires, and consequent Iv iiiu-t 

 generate an electric current from the point :i t which 

 the tension is -rreater to t-hat at which it is le-s. If a 

 multiplier is inserted in the applied \\iiv, the needle 

 will be deflected. This is a> t rue of a n^'iilar as of an 

 irregular conductor. If in the 1 o ly .1 // (ti^. -I.".), 

 electricity moves along \arions paths, and if, as we 

 have seen, different ten-ions pre\ail at t\\o points in 

 such a path, a current mii.-t ari-e if (he ends of a Lent 

 wire are applied to these point-, and if the bent wire 

 i- Hipplied with a multiplier the needle \\ill be de- 



