Bulbar Focus Tube with Carbon regeneration

Ref. B22

This peculiarly shaped tube bears no maker’s name.  The only information about it is a label “G.B.Paravia & C” fixed on the cathode side of the glass wall, corresponding to a library established in Turin since 1802, and is still in business, well-known for publishing and selling educational material.

Dating back probably to the middle third of the 20th century, it is 13.5” (34cms) long with a 4” (10cms) bulb. It has a concave aluminum cathode, partly discolored, a rod-type aluminum anode, an anti-cathode and target of unknown material and regeneration by a cylindrical carbon inclusion freely moving in an accessory chamber.

Note the spherical “swelling” of the glass sleeve of the cathode arm, holding the cathode firmly in place inside the tube wall.