The Turn Of The Century Electrotherapy Museum http://www.electrotherapymuseum.com Spark Gap with accurate distance readout H. G. FIscher Spark Gap, 1/4" Tungsten Electrodes, and Dial Gauge. Gauge reads to .001", but ten-thousanths of an inch can be estimated by eye Using JAVATC: http://www.classictesla.com/java/javatc.html (a nifty highly complex program by Bart Anderson) ...I can figure out that with a 3500V 8mA transformer, .015 mfd condenser, and gap spacing of .05625", the charging voltage is 4950 volts, the gap setting is 4914 peak volts, and the gap will fire when 99.3% charged with an effective energy of .18 joules.  It'll operate at 17 BPS, with a time to arc voltage of 58.169 ms.  Those details will be useful in the analysis of lichtenberg figures and phantom streams, esp. in conjunction with the work of Peder Pedersen. ("On The Lichtenberg Figures", 3 volumes) These are going to the best Tesla Coiler on the planet... Adjustable Spark Gap with ratchet wheel to limit movement - 5/16 - 40 TPI thread pitch. Experimental Bulldog - er, Spark Gap with plane surface and pointed edge surface Sumo:  [yawn] "not another spark gap..." (C) Jeff Behary, 2010