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 January 2010 and filming took place between May and June 2010. The show was to be broadcast in high-definition television. Filming for the second season of "The Amazing Race en Discovery Channel" lasted for 25 days and covered nearly . The second season spanned eight countries in two continents. Among them, 4 were unvisited countries, including Bolivia, Guatemala, Ecuador and Venezuela. Previously visited countries were Mexico, Brazil and Argentina. Colombia was also a previously visited country never visited in the original American version at the time of air, it will later be visited in the twenty-eighth season in 2016. The