174 PHYSIOLOGY OF MUSCLES AND NERVES. 



instead of these two wires a number of separate wires 

 are used, then the same thing happens ; and if the wires 

 are welded together into a common conducting body, 

 this does not essentially alter the conditions of the fall, 

 so that we may imagine the whole body to consist of 

 these separate wires, in each of which a definite flill, 

 the steepness of which depends on the length of the 

 particular wire, prevails. These wires are, however, 

 merely paths along which the electric currents pass, 

 and of which we have already spoken. In the case 

 of these paths also definite falls must prevail, and these 

 must be more steep in proportion as the points at 

 which the electric currents 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 exhibit 

 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 must effect a disturbance in the natural elec- 

 tricity wdthin the applied wires, and consequently must 

 generate an electric current from the point at which 

 the tension is greater to that at which it is less. If a 

 multiplier is inserted in the applied wire, the needle 

 will be deflected. This is as true of a regular as of an 

 irregular conductor. If in the body A B (fig. 43), 

 electricity moves along various paths, and if, as we 

 have seen, different tensions prevail at two points in 

 such a path, a current must arise if the ends of a bent 

 wire are applied to these points, and if the bent wire 

 is supplied with a multiplier the needle will be de- 



