original antique american portable research laboratory benchtop high-voltage induction coil fabricated by or for elmer g. willyoung & co., betz building, philadelphia, pa. the early medical instrument is mounted on a solid cherry wood base retaining the original varnished finish. the primary coil, consisting of copper wire tape wrapped around an iron metal core is heavily insulated in a mixture of beeswax and/or resin. the interrupter mechanism, terminals, etc. are mostly intact. the original lightly incised brass metal manufacturers plaque is prominently displayed on the wooden base. an induction coil or "spark coil" is a type of disruptive discharge coil. it is a type of electrical transformer used to produce high-voltage pulses from a low-voltage direct current (dc) supply. to create the flux changes necessary to induce voltage in the secondary, the direct current in the primary is repeatedly interrupted by a vibrating mechanical contact called an interrupter. michael faraday discovered the principle of induction, faraday's induction law, in 1831 and did the first experiments with induction between coils of wire. the induction coil was invented by the irish scientist and catholic priest nicholas callan in 1836 at the st. patrick's college, maynooth and improved by william sturgeon and charles grafton page. the early coils had hand cranked interrupters, invented by callan and antoine philibert masson (1806-1860). induction coils were used to provide high voltage for early gas discharge and crookes tubes and other high voltage research. they were also used to provide entertainment (lighting geissler tubes, for example) and to drive small "shocking coils", tesla coils and violet ray devices used in quack medicine. they were used by hertz to demonstrate the existence of electromagnetic waves, as predicted by james maxwell and by lodge and marconi in the first research into radio waves. their largest industrial use was probably in early wireless telegraphy spark-gap radio transmitters and to power early cold cathode x-ray tubes from the 1890's to the 1920's, after which they were supplanted in both these applications by ac transformers and vacuum tubes. however their largest use was as the ignition coil or spark coil in the ignition system of internal combustion engines, where they are still used, although the interrupter contacts are now replaced by solid state switches. a smaller version is used to trigger the flash tubes used in cameras and strobe lights. measures 35 x 18 x 19 inches.