WHY PROGRESS IS BY LEAPS. 219 



impenetrable, that Franklin less than five generations ago should 

 detect that lightning and electricity are one, and that only in our 

 day at the hands of Hertz has it been demonstrated that the elec- 

 tric pulse differs only from the wave of heat or light in being 

 longer. This discovery of Hertz was long ago foreshadowed in 

 the observation that heat can have electric origin. One of the 

 first fruits of electrical study was the finding that some metals 

 transmit electricity better than others, and that the efficacy of a 

 conductor depends in part on its size. When a conducting wire 

 was reduced to extreme tenuity, the resistance to the current's 

 passage, with striking resemblance to common friction, expressed 

 itself as vivid heat. The miner and the gunner at once saw their 

 opportunity to use electricity to touch off their fuses and to ex- 

 plode at the same instant, with an effect before impossible, a round 

 of separate charges. 



Coi3ying the methods of the miner, the mechanic and the 

 chemist very often find electric heat the most advantageous they 

 can employ. "When the broken blade of a propeller is to be re- 

 paired, the electric welder can be taken to its work instead of the 

 work having to go to a stationary welder. When electric heat is 

 carried into a crucible through almost impenetrable walls of gyp- 

 sum, it enters the very heart of its task without the offense and 

 waste of flame. Thus to-day is flame face to face with a sup- 

 planter in the shape of its long undetected twin. Until this gen- 

 eration flame alone was the source not only of heat, but of the 

 beam of candle, lamp, and gas jet. To-day myriads of electric 

 bulbs are aglow without flame — indeed, just because combustion is 

 rendered impossible by the rigid exclusion of air. As these in- 

 candescent lamps were long ago prophesied in the miner's electric 

 fuse, so also has the first simple process of the electroplater led 

 up to an art incomparably more important. To-day not surfaces 

 merely, but large masses, chiefly of statuary, are built in cool 

 tanks by electricity. Let the current become cheaper still, and 

 the founder may find the remainder of his business transferred to 

 this formidable rival, the warping heats of sand molds banished, 

 the scorching temperature of crucible and ladle a reminiscence. 

 The same fate may be in store for the smelting furnace. Already 

 vast quantities of copper are refined electrolytically, and an au- 

 spicious beginning has been made in using electricity for the whole 

 process of parting metal from ore. Thus methods which com- 

 menced in dismissing flp.me end boldly by eliminating heat itself. 

 This usurping electricity, it may be said, usually finds its source, 

 after all, in fire under a steam boiler. True, but mark the harness- 

 ing of Niagara, of the Lachine Rapids near Montreal, of a thou- 

 sand streams elsewhere. In the years of the near future motive 

 power of Nature's giving is to be wasted less and less, and per- 



