Gundelach X-ray Tube
This is an X-ray image of a Gundelach tube, a two bi-anode cold cathode X-ray tube originally introduced in the late 1890s (right after Röntgen’s discovered the ‘X-rays’) and typically manufactured until 1920s. (The picture above was taken with a Nikon's XTH225-ST CT system housing a modern X-ray tube)
—Herminoso Villarraga-Gómez, Nikon Metrology, Inc., Americas