This tube, of the second decade of the 20^th Century, is  25”(63 cms) long with a 6” (15cms) bulb, was made by the Kesselring X-Ray Tube Company, Chicago, Il., and was intended for use in conjunction with a high frequency high voltage (up to 100kV) generator, such as a Tesla coil.

         Compared to other gas discharge x-ray tubes, it presents two peculiar characteristics, namely the absence of any external electrical connection to the anti-cathode, and the presence of a conical copper funnel-shaped attachment on the rear side of the anti-cathode.  X-rays are produced by the impact of the electrons on the tungsten target placed in the path of the electron stream flowing from the cathode towards the anode. As to the conical attachment on the rear of the anti-cathode, it presumably helps shaping the electron beam.

         Regeneration is by the small cylindrical secondary chamber on the upper side of the bulb, containing a whitish fiber-like material, probably asbestos.