Cathode Ray Tube


Accession Number:


A five-mineral fluorescing cathode ray tube or Crookes tube consisting of a pear-shaped upright glass bulb mounted above a turned wooden base. Within the bulb, there are five green mineral samples held by strands of glass that have been melted to clasp the stones tightly. At the top and side of the bulb are electrodes contained within cylindrical glass arms.

Alternative Name: Crookes Tube

Primary Materials:

Wood, Glass, Metal: Copper Alloy, Minerals

Markings: Old inventory number = phy28.

Dimensions (cm): Height = 33, Base Diameter = 13


5 Minerals fluoresce under the bombardment of cathode rays. Possibly used for spectroscopy demonstrations.


Excellent: The glass is intact through the length of the tube. The wooden base is in good condition, although worn in places. The metal components are oxidized on their surface, but otherwise in good condition.

Associated Instruments:


Date of Manufacture: 1890s?


Department of Physics, University of Toronto

Historical Notes:

In October 1898, instructor and future professor J.C. McLennan visited the Geissler Establishment, in Bonn, Germany. The Geisslers were famous for the manufacture of Crookes Tubes. McLennan reported in a letter back to Professor James Loudon that he had purchased some of these for the Toronto physics laboratory, including one with a “phosphorescent mineral”, which, he reported, “gives the most beautiful effect that I have seen.”

There are numerous examples of phosphorescent mineral tubes in the collection. It is possible that one, or more, of these were purchased by McLennan during his 1898 trip to Bonn.