Nikola Tesla - Free-Energy Devices

362 INVENTIONS OF NIKOLA TESLA.not be maintained without the medium being constantly renewed.A vacuum cannot, according to all evidence, be permanentlymaintained around a hot body.In these constructions, before mentioned, the small bulb insidewould, at least in the first stages, prevent all bombardmenta* - against the outer large globe. It occurred to me then to ascertainhow a metal sieve would behave in this respect, and severalbulbs, as illustrated in Fig. 195, were prepared for this purpose.r. In a globe &, was mounted a thin filament f (or button) upon aplatinum wire w passing through a glass stem and leading to theoutside of the globe. The filament /"was surrounded by a metalsieve s. It was found in experiments with such bulbs that a sievewith wide meshes apparently did not in the slightestaffect thebombardment against the globeb. When the vacuum was high,the shadow of the sieve was clearly projected against the globeand the latter would get hot in a short while. In some bulbs thesieve .s was connected to a platinum wire sealed in the glass.When this w r ire was connected to the other terminal of the inductioncoil (the E. M. F. being kept low in this case), or to an insulatedplate, the bombardment against the outer globe1) wasdiminished. By taking a sieve with fine meshes the bombardmentagainst the globe b was always diminished, but even thenif the exhaustion was carried very far, and when the potential ofthe transformer was very high, the globe1} would be bombardedand heated quickly, though no shadow pf thesieve was visible,owing to the smallness of the meshes. But a glass tube or othercontinuous body mounted so as to surround the filament, did entirelycut off the bombardment and for a while the outer globe bwould remain perfectly cold. Of course when the glass tubewas sufficiently heated the bombardment against the outer globecould be noted at once. The experiments with these bulbsseemed to show that the speeds of the projected molecules orparticles must be considerable (though quite insignificant whencompared with that of light), otherwise it would be difficult tounderstand how they could traverse a fine metal sieve withoutbeing affected, unless it were found that such small particles oratoms cannot be acted upon directly at measurable distances.In regard to the speed of the projected atoms, Lord Kelvin hasrecently estimated it at about one kilometre a second or thereaboutsin an ordinary Crookes bulb. As the potentials obtainablewith a disruptive discharge coil are much higher than with or-