498 THE POPULAR SCIENCE MONTHLY. 



probably the force with wliicli chemistry is most deeply con- 

 cerned. 



It has been computed that in a single cubic foot of the ether 

 which fills all space there are locked up ten thousand foot-tons 

 of energy which have hitherto escaped notice. To unlock this 

 boundless store and subdue it to the service of man is a task 

 which awaits the electrician of the future. The latest researches 

 give well-founded hopes that this vast storehouse of power is not 

 hopelessly inaccessible. Up to the present time we have been 

 acquainted with only a very narrow range of ethereal vibrations, 

 from extreme red on the one side to ultra-violet on the other — say 

 from three ten-millionths of a millimetre to eight ten-millionths 

 of a millimetre. Within this comparatively limited range of 

 ethereal vibrations, and the equally narrow range of sound vibra- 

 tions, we have been hitherto limited to receive and communicate 

 all the knowledge which we share with other rational beings. 

 "Whether vibrations of the ether, slower than those wliich affect 

 us as light, may not be constantly at work around us, we have 

 until lately never seriously inquired. But the researches of Lodge 

 in England, and Hertz in Germany, give us an almost infinite 

 range of ethereal vibrations or electrical rays, from wave-lengths 

 of thousands of miles down to a few feet. Here is unfolded to us 

 a new and astonishing universe — one which it is hard to conceive 

 should be powerless to transmit and impart intelligence. 



Experimentalists are reducing the wave-lengths of the elec- 

 trical rays. With every diminution in size of the apjDaratus 

 the wave-lengths get shorter, and could we construct Leyden 

 jars of molecular dimensions the rays might fall within the nar- 

 row limits of visibility. We do not yet know how the molec- 

 ule could be got to act as a Leyden jar ; yet it is not improba- 

 ble that the discontinuous phosphorescent light emitted from 

 certain of the rare earths, when excited by a high - tension cur- 

 rent in a high vacuum, is really an artificial production of 

 these electrical rays, sufficiently short to affect our organs of sight. 

 If such a light could be produced more easily and more regularly, 

 it would be far more economical than light from a flame or from 

 the arc, as very little of the energy in play is expended in the 

 form of heat-rays. Of such production of light. Nature supplies 

 us with examples in the glow-worm and the fire-flies. Their light, 

 though sufficiently energetic to be seen at a considerable distance, 

 is accompanied by no liberation of heat capable of detection by 

 our most delicate instruments. 



By means of currents alternating with very high frequency. 

 Prof. Nikola Tesla has succeeded in passing by induction through 

 the glass of a lamp energy sufficient to keep a filament in a state 

 of incandescence without the use of connecting wires. He has 



