Fig. 11.
Disruptive "Tesla" Coil.
For Fig. 11 the specification is as follows: Secondary, 300 turns of No. 30 B & S silk-covered magnet wire, wound on rubber tube or rod, and the ends encased in glass or rubber tubes. This is inserted into the primary, which consists of two coils, each of 20 turns No. 16 B & S rubber-covered wire, wound separately on a long rubber tube not less than ⅛ inch thick. The last tube must be large enough to be very loose when the secondary coil is inserted in it, and it must project at least two inches over each end of the secondary. A hard rubber division must be placed between these primary coils. The four ends of the latter coils are connected C C to two condensers and D D to two discharger balls, the secondary wires going to the exhibitive apparatus. A further description of these connections is to be found in [Chapter XII]., also notes upon the use of the disruptive coil.
Coils for Gas Engines.
These are either primary only or primary and secondary. Two to three pounds of No. 14 B & S magnet wire are wound on an iron wire core eight to ten inches in length by one inch in diameter. The contact is made and broken in the igniter of the engine as at the wipe spring of a ratchet gas burner. Four to eight large cells of dry battery are used, or eight cells Edison-Lalande—iron-clad type. Number of cells varies with size of coil needed, some classes of engines require a heavier spark than others to ignite the vapor.
When a primary and secondary are used, the primary should be made of two or three layers No. 14 B & S magnet wire, and a secondary of one pound No. 34 B & S magnet wire. There can be an independent contact breaker or the coil can be made up similar to a one-half inch spark Ruhmkorff coil (see Chapter I.).
Fig. 12.