Nikola Tesla - Free-Energy Devices

HIGH FREQUENCY AND HIGH POTENTIAL CURRENTS. 237Some experiences have already been gained in this direction,and I will dwell on them briefly, in the hope that they mightprove useful.The heating of a conducting body inclosed in a bulb, and connectedto a source of rapidly alternating electric impulses, isdependent on so many things of a different nature, that it wouldbe difficult to give a generally applicable rule under which themaximum heating occurs. As regards the size of the vessel, Ihave lately found that at ordinary or only slightly differingatmospheric pressures, when air is a good insulator, and hencepractically the same amount of energy by a certain potential andfrequency is given off from the body, whether the bulb be smallor large, the body is brought to a higher temperature if enclosedin a small bulb, because of the better confinement of heat in thiscase.At lower pressures, when air becomes more or less conducting,or if the air be sufficiently warmed to become conducting, thebody is rendered more intensely incandescent in a large bulb,obviously because, under otherwise equal conditions of test, moreenergy may be given off from the body when the bulb is large.At very high degrees of exhaustion, when the matter in thebulb becomes " radiant," a large bulb has still an advantage, buta comparatively slight one, over the small bulb.Finally, at excessively high degrees of exhaustion, which cannotbe reached except by the employment of special means, thereseems to be, beyond a certain and rather smallsize of vessel, noperceptible difference in the heating-.These observations were the result of a number of experiments,of which one, showing the effect of the size of the bulb at a highas itdegree of exhaustion, may be described and shown here,presents a feature of interest. Three spherical bulbs of 2 inches,3 inches and 4 inches diameter were taken, and in the centre ofeach was mounted an equal length of an ordinary incandescentlamp filament of uniform thickness. In each bulb the piece offilament was fastened to the leading-in wire of platinum, containedin a glass stem sealed in the bulb care ; being taken, ofcourse, to make everything as nearly alike as possible. On eachglass stem in the inside of the bulb was slipped a highly polishedtube made of aluminum sheet, which fitted the'stem and was heldon itby spring pressure. The function of this aluminum tube willbo explained subsequently. In each bulb an equal length of fila-