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Cathode Ray Tube with Five Minerals


A five-mineral fluorescing cathode ray tube or Crookes tube consisting of a par-shaped upright glass bulb mounted above a turned wooden base. Within the bulb, there are five minerals held by glass fingers. At the top and side of the bulb are electrodes contained within cylindrical glass arms.

Accession Number:

Alternative Name: Crookes tube

Primary Materials:

Wood, Glass, Metal: Copper Alloy, Minerals


An old catalogue number appears on an attached label = “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: c. 1890s


Department of Physics, University of Toronto

Additional Information and References:

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 at least one with a “phosphorescent mineral”, which, he reported, “gives the most beautiful effect that I have seen.” (McLennan, 1898)

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.

Letter from J.C. McLennan to J. Loudon, October 10, 1898. University of Toronto Archives B1972-0031 Box 004 File 43

Historical Notes: