Nikola Tesla Books
CHAPTER V. THE SPARK GAP. The function of the spark gap is to provide a gap between suitable metal electrodes for the high potential current stored up in the condenser to leap across, thereby setting up the electrical oscillations. The gap, in its simplest form, is a pair of zinc cylinders placed end to end and insulated from each other; a means is provided whereby the distance between the electrodes may be adjusted to the necessary point. This adjustment may be provided conveniently by threading the rods of zinc and supporting them in standards in which tapped holes have been prepared. A large knob or disc of fibre on one electrode enables the operator to make the adjustment while the current is passing. This simple gap is open to many objections when the higher powers are encountered, although it is quite satisfactory for use with the induction coil sets or small transformer outfits. On transformers of ½ K. W. or over, the simple gap quickly becomes heated to excess and the operation is unsatisfactory. An improvement is afforded by placing radiators on the electrodes to aid in the dissipation of the heat as it is formed. A further improvement is the use of larger electrodes of zinc and a step still further is taken if the electrodes are made of nickel-steel; owing to the difficulty of work this substance, however, it is not considered within the reach of the experimenter. It is 30
