Nikola Tesla - Free-Energy Devices

306 INVENTIONS OF NIKOLA TESLA.are slipped on the rods, the latter serving to set the points of therods at [acertain suitable distance by means of screws # 3 s ands,the former to draw the points apart. When it is desired to startthe arc, one of the large rubber handles h Ji istapped quicklywith the [hand, whereby the points of the rods are brought incontact but are instantly separated by the springs r r^Such anarrangements-has been found to be often necessary, namely incases when the E. M. r. was not large enough to cause the dischargeto break through the gap, and also when it was desirable to avoidshort circuiting of the generator by the metallic contact of therods. The rapidity of the interruptions of the current with amagnet depends on the intensity of the magnetic field and on theFIG.ICG.potential difference at the end of the arc. The interruptions aregenerally in such quick succession as to produce a musical sound.Years agoit was observed that when a powerful induction coilis discharged between the poles of a strong magnet, the dischargeproduces a loud noise, not unlike a small pistol shot, It wasvaguely stated that the spark was intensified by the presence ofthe magnetic field. It is now clear that the discharge current,flowing for some time, was interrupted a great number of timesby the magnet, thus producing the sound. The phenomenon isespecially marked when the field circuit of a large magnet ordynamo is broken in a powerful magnetic field.