Nikola Tesla U.S. Patent 512,340 - Coil for Electro-Magnets Patent Wrapper Page 3

TO ALL WHOM IT MAY CONCERN: Be it known that I, NIKOLA TESLA, a citizen of the United States, residing at New York, in the Count y and State of New York, have invented certain new and useful Improvements in COILS FOR ELECTRO-MAGNETS AND OTHER APPARATUS, of which the following is a specification, reference being had to the drawing accompanying and forming a part of the same. In electric apparatus or systems in which alternating currents are employed the self-induction of the coils or conductors may, and, in fact, in many cases does operate disadvantageously by giving rise to false currents which often reduce what is known as the commercial efficiency of the apparatus composing the systém or operate detrimentally in other respects. The effects of self-induction, above referred to, are known to be neutralized by proportioning to a proper degree the capacity of the circuit with relation to the self-induction and frequency of the currents. This has been accomplished heretofore by the use of condensers constructed and applied as separate instruments. My present invention has for its object to avoid the employment of condensers which are expensive, cumbersome and difficult to maintain in perfect condition, and to so construct the coils themselves as to accomplish the same ultimate object. I would here state that by the term coils I desire to include generally -13