ELECTRICITY AT THE WORLD'S FAIR. 43 



be moved along the track as the work proceeds. The current to 

 supply both the motors and the converters is taken from the line 

 wire by the ordinary trolley arm. In making the weld the earth 

 is removed from about the joint, clamps applied, and the current 

 sent through the rail ends until these are brought to a welding 

 heat. 



Another method of utilizing the electric current in the work- 

 ing of metals shown by the Thomson Company is due to M. de 



FIG. 9. TIRE WELDER. 



Meritens, a well-known French inventor and constructor of dyna- 

 mos. This consists in forming an arc between the object to be 

 heated and a movable electrode carried in the hand of the opera- 

 tor. In this case the work forms one terminal of the electric cir- 

 cuit and the hand tool the other. This hand tool consists simply 

 of a stick of ordinary arc-light carbon mounted in a suitable 

 holder, and connected with the circuit by a flexible cable. 



The workman is by this simple device provided with a tool of 

 remarkable range and flexibility. He has at his command the 

 enormous temperature of the electric arc, yet in such a form that 

 he can vary it from the heat of a taper to full intensity, and reach 

 with it parts of his work that would otherwise be inaccessible. 



