Menu Close

Oxide-Coated Cathode Ray Tube


A 20 cm glass bulb with two 3 cm projections on opposite sides. The glass bulb contains three electrodes. A 6 cm tube is mounted inside the large bulb. The bulb is supported by a metal collar, supported by twin metal rods emerging from a turned wooden base. The side of the bulb near the collar reads “861” and a large capital ‘G’, with a set of scales in the middle of the ‘G’.

Accession Number:

Alternative Name: Crookes tube

Primary Materials: Wood, Metal, Glass

Markings: Old inventory number = phy68.

Dimensions (cm):

Height = 35, Base Diameter = 13, Bulb Diameter = 20


When a current is applied, the thin strip in the middle of this tube (likely platinum coated with calcium oxide) acts as a cathode without an external anode. According to it’s catalogue, this device was used to demonstrate the circular bending of cathode rays in a magnetic field and to determine the relationship between the charge and the mass of an electron.


Associated Instruments:


Date of Manufacture:


Additional Information and References:

Historical Notes:

Likely made by German manufacturers Richard Muller-Uri and Max Kohl.