Pressler Cold Cathode X-Ray Tubes (ca. 1910-1950)
Two similar gas discharge tubes manufactured by the Otto Pressler company of Leipzig, Germany. Even though the company was founded in 1897, they are still in business! If something glows and is made of glass, they have it! Unfortunately, it has been a long time since they last produced X-ray tubes.
It is fairly safe to guess that these particular tubes were manufactured sometime between 1910 and 1950. But in all likelihood the date of manufacture was closer to 1950 than 1910.
In the upper of the two tubes, the anticathode (target) is on the long axis of the tube and the anode (two twisted aluminum wires) comes in at a 45 degree angle behind the target.
The arrangement of the anode and anticathode are reversed in the lower tube. Another difference between the two tubes: the target is somewhat heavier in the second tube.
One slightly "odd" thing that the tubes have in common: their cathodes are located deeper into the glass arms than is usual—in most gas discharge X-ray tubes the cathode is located right at the junction between the glass arm and the spherical bulb. The probable result would be that the tubes required higher operating voltages than would otherwise be the case.
Each tube has two short extensions projecting from the glass arm (photo to right) that surrounds the cathode. One of these extensions, the regulator, contains a material (charcoal?) that when heated in a flame would emit a gas and increase the pressure inside the tube making the latter "softer." The other extension, diagonally opposite the regulator, is the sealed extension that was used to pull the vacuum during manufacture.
I must admit that they are not particularly interesting. These tubes would have been intended for classroom demonstrations rather than actual use in medicine or industry.
Size: Approximately 11" long with 3.5" bulb diameter