Patent specifications for the Tesla coil. TESLA, NIKOLA. 1856-1943. [Tesla Coil] Complete Specification for Patent No. 8575 Improved methods of and apparatus for generating and utilizing electric energy for lighting purposes. Date of application, 19th May, 1891-Accepted 20th June, 1891. London: Darling & Son for His Majesty's Stationery Office, 1891. 8vo (260 x 184 mm). 1 Plate. Disbound; stitching holes in left margin, left margin a bit ragged. Light toning but very good. Library stamps (one embossed) on the first page. FIRST EDITION of the British patent for the Tesla coil, granted on 20 June 1891, three days prior to the U.S. patent for this device. Tesla applied for the U.S. patent on 25 April 1891 but did not receive it until 23 June. The Tesla coil is an electrical resonant transformer circuit that produces high-voltage, low-current, high-frequency alternating-current electricity. Although Tesla patented many similar circuits during this period, the present patent represents the first to contain all the elements of the Tesla coil: High-voltage primary transformer, capacitor, spark gap, and air core 'oscillation transformer.' Tesla used his coil to conduct innovative experiments in electrical lighting, high-frequency AC phenomena and wireless transmission of electricity. In the first part of the 20th century Tesla coils found a commercial application in wireless telegraphy and electrotherapy; today their dramatic and colorful electrical discharges provide entertainment at science museums and special effects for movies and television. For further information on this lot please visit Bonhams.com For further information about this lot please visit the lot listing