Nikola Tesla - Free-Energy Devices

220 INVENTIONS OF NIKOLA TESLA.the terminal only upon the hand being brought much nearer.If the oscillation of the primary current is rendered intermittentby some means or other, there is a corresponding throbbing ofthe streams, and now the hand or other conducting object maybe brought in still greater proximity to the terminal without aspark being caused to jump.Among the many beautiful phenomena which may be producedwith such a coil, I have here selected only those which appearto possess some features of novelty, and lead us to someconclusions of interest. One will not tind it at all difficult toproduce in the laboratory, by means of it, many other phenomenawhich appeal to the eye even more than these here shown, butpresent no particular feature of novelty.Early experimenters describe the display of sparks produced byan ordinary large induction coilupon an insulating plate separatingthe terminals. Quite recently Siemens performed some experimentsin which fine effects were obtained, which were seenby many with interest. No doubt large coils, even if operatedwith currents of low frequencies, are capable of producingbeautiful effects. But the largest coil ever made could not, byfar, equal the magnificent display of streams and sparks obtainedfrom such a disruptive discharge coil when properly adjusted.To give an idea, a coil such as the present one will cover easilya plate of one metre in diameter completely with the streams.The best way to perform such experiments is to take a very thinrubber or a glass plate and glue on one side of it a narrow ringof tinfoil of very large diameter, and on the other a circularwasher, the centre of the latter coinciding with that of the ring,and the surfaces of both being preferably equal, so as to keepthe coil well balanced. The washer and ring should be connectedto the terminals by heavily insulated thin wires. It is easy inobserving the effect of the capacity to produce a sheet of uniformstreams, or a fine network of thin silvery threads, or amass of loud brilliant sparks, which completely cover the plate.Since I have advanced the idea of the conversion by means ofthe disruptive discharge, in my paper before the American Instituteof Electrical Engineers at the beginning of the past year,the interest excited in it has been considerable. It affords us ameans for producing any potentials by the aid of inexpensivecoils operated from ordinary systems of distribution, and whatisperhaps more appreciatedit enables us to convert cunvnt* !'