Nikola Tesla film in his laboratory in previous experiments (later identified as ""Roentgen rays"" or "X-Rays"). His early experiments were with Crookes tubes, a cold cathode electrical discharge tube. Tesla may have inadvertently captured an X-ray image—predating, by a few weeks, Wilhelm Röntgen's December 1895 announcement of the discovery of X-rays when he tried to photograph Mark Twain illuminated by a Geissler tube, an earlier type of gas discharge tube. The only thing captured in the image was the metal locking screw on the camera lens. In March 1896, after hearing of Wilhelm Röntgen's discovery of X-ray and X-ray imaging (radiography), Tesla
The Amazing Race en Discovery Channel 2 route markers in this season were coloured blue and black, including the clue envelopes and the Pit Stop. None of the eliminated teams were present at the Finish Line. Applications were accepted from 13 December 2009 and finished on 8 February 2010. Semi-finalist interviews were held sometime in March 2010 and the final casting interviews took place around April 2010. According to Discovery's official website, the four official sponsors of the second season of "The Amazing Race en Discovery Channel" were Bridgestone, Samsung, Visa and Wii Party. The sponsors played a major role in the series by providing prizes and