Nikola Tesla - Free-Energy Devices

HIGH FREQUENCY AND HIGH POTENTIAL CURRENTS. 239mounted in its centre is the best to employ. By experience itlias been demonstrated that in such a globe a refractory body ofa given bulk is more easily brought to incandescence than whendifferently shaped bulbs are used. There is also an advantage ingiving to the incandescent body the shape of a sphere, for selfevidentreasons. In any case the body should be mounted in thecentre, where the atoms rebounding from the glass collide. Thisobject is best attained in the spherical bulb ;but it is also attainedin a cylindrical vessel with one or two straight filamentscoinciding with its axis, and possibly also in parabolical or sphericalbulbs with refractory body or bodies placed in the focus orfoci of the same; though the latter is not probable, as the electrifiedatoms should in all cases rebound normally from thesurface they strike, unless the speed were excessive, in whichcase they would probably follow the general law of reflection.]S r o matter what shape the vessel may have, if the exhaustion below, a filament mounted in the globe is brought to the samedegree of incandescence in all parts but if the exhaustion be;high and the bulb be spherical or pear-shaped, as usual, focalpoints form and the filament is heated to a higher degree at ornear such points.To illustrate the effect, I have here two small bulbs which arealike, only one is exhausted to a low and the other to a very highdegree.When connected to the coil, the filament in the formerglows uniformly throughout all its length whereas in the ;latter,that portion of the filament which is in the centre of the bulbglows far more intensely than the A rest. curious is point thatthe phenomenon occurs even if two filaments are mounted in abulb, each being connected to one terminal of the coil, and, whatis still more curious, if they be very near together, provided thevacuum be very high. I noted in experiments with such bulbsthat the filaments would give way usually at a certain point, andin the first trials I attributed it to a defect in the carbon. Butwhen the phenomenon occurred many times in succession Irecognized its real cause.In order to bring a refractory body inclosed in a bulb to incandescence,it is desirable, on account of economy, that all theenergy supplied to the bulb from the source should reach withoutloss the body to be heated ;from there, and from nowhere else,it should be radiated. It is,of course, out of the question toreach this theoretical result, but it is possible by a proper constructionof the illuminatingdevice to itapproximate more or less.