This exhibit is a Margo Fleming Valve. Fleming as it uses the Fleming effect.
The anode is a helix of stout wire and the filament is a single strand.
The original box.
Thanks to Joe Gruber for sending the images.
The thin glass tube envelope is 16 mm in diameter and, including the peanut base pins, is 50 mm tall.
Reference: Joe Gruber.
Updated November 26, 2020. shape:thin.glass.tube construction:pinch type:diode age:pre.1920 base:peanut pins:4 pin: