Nikola Tesla - Free-Energy Devices

308 INVENTIONS OF NIKOLA TESLA.It is desirable to exclude the light as perfectly as possible, as itinterferes with some experiments.This form of discharger is simpleand very effective when properly manipulated. The airbeing warmed to a certain temperature, has its insulating poweritimpaired becomes;dielectrically weak, as it were, and the consequenceis that the arc can be established at much greater distance.The arc should, of course, be sufficiently insulating toallow the discharge to pass through the gap disruptively. Thearc formed under such conditions,be made ex-when long, maytremely sensitive, and the weak draught through the lampchimney c is quite sufficient to produce rapid interruptions. Theadjustment is made by regulating the temperature and velocityof the draught. Instead of using the lamp,it answers the purposeto provide for a draught of warm air in other ways. Avery simple way which has been practiced is to enclose the arcin a long vertical tube, with plates on the top and bottom forregulating the temperature and velocity of the air current.Some provision had to be made for deadening the sound.The airmay be rendered dielectrically weak also by rarefaction.Dischargers of this kind have likewise been used by mein connection with a magnet. A large tube is for this purposeprovided with heavy electrodes of carbon or metal, betweenwhich the discharge is made to pass, the tube being placed in apowerful magnetic field. The exhaustion of the tube is carriedto a point at which the discharge breaks through easily, but thepressure should be more than Y5 millimetres, at which the ordi.nary thread discharge occurs. In another form of discharger,combining the features before mentioned, the discharge wasmade to pass between two adjustable magnetic pole pieces, thespace between them being kept at an elevated temperature.It should be remarked here that when such, or interruptingdevices of any kind, are used and the currents are passed throughthe primary of a disruptive discharge coil, it is not, as a rule, ofadvantage to produce a number of interruptions of the currentper second greater than the natural frequency of vibration of thedynamo supply circuit, which is ordinarily small. It should alsoba pointed out here, that while the devices mentioned in connectionwith the disruptive discharge are advantageous under certainconditions, they may be sometimes a source of trouble, asthey produce intermittences and other irregularities in the vibrationwhich it would be very desirable to overcome.