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INVENTION'S OE NIKOLA TESLA.

such as it has been heretofore regarded as necessary to use. Thecurrent in either branch may be used in the same way and forthe same purposes as any other direct current—that is, it may bemade to charge secondary batteries, energize electro-magnets, orfor any other analogous purpose.

Fig. 220 represents a plan of directing the alternating currentsby means of devices purely electrical in character. Figs. 221,222, 223, 224, 225, and 226 are diagrams illustrative of otherways of carrying out the invention.

In Fig. 220, a designates a generator of alternating currents,and b b the main or line circuit therefrom. At any given pointin this circuit at or near which it is desired to obtain ■ direct cur-rents, the circuit b is divided into two paths or branches c d. Ineach of these branches is placed an electrical generator, whichfor the present we will assume produces direct or continuous cur-

Fig. 220.

rents. The direction of the current thus produced is opposite inone branch to that of the current in the other branch, or, con-sidering the two branches as forming a closed circuit, the gene-rators e f are connected up in series therein, one generator ineach part or half of the circuit. The electromotive force of thecurrent sources e and f may be equal to or higher or lower thanthe electromotive forces in the branches c l>, or between the pointsx and y of the circuit b b. If equal, it is evident that currentwaves of one sign will be opposed in one branch and assisted inthe other to such an extent that all the waves of one sign willpass over one branch and those of opposite sign over the other.If, on the other hand, the electromotive force of the sources e fbe lower than that between x and y, the currents in bothbranches will be alternating, but the waves of one sign will pre-ponderate. One of the generators or sources of current e or fmay be dispensed with; but it is preferable to employ both, if