110

INVENTIONS OF NIKOLA TESLA.

of this core, he makes it of thin strips, plates, or wires of softiron electrically insulated as far as practicable. Upon this coreare wound, say, four coils, bbb' b', used as primary coils, and forwhich long lengths of comparatively tine wire are employed.Over these coils are then wound shorter coils of coarser wire, c co' c', to constitute the induced or secondary coils. The construc-tion of this or any equivalent form of converter may be carriedfurther, as above pointed out, by inclosing these coils with iron—as, for example, by winding over the coils layers of insulatediron wire.

The device is provided with suitable binding posts, to which

Figs. 92 and 9i5.

min

the ends of the coils are led. The diametrically opposite coilsb b and b' b' are connected, respectively, in series, and the fourterminals are connected to the binding posts. The inducedcoils are connected together in any desired manner. For ex-ample, as shown in Fig. 9-f, c c may be connected in multiplearc when a quantity current is desired—as for running a groupof incandescent lamps—while o' o' may be independently con-nected in series in a circuit including arc lamps or the like. Thegenerator in this system will be adapted to the converter in the