Menu Close

Cathode Ray Tube with One Mineral


A black turned wooden base with a 19cm glass tube vertically mounting on top of the wooden base. On the lower part of the glass tube there is a 2cm projection which contains the electrode. Inside the glass tube there is a greenish mineral which is supported by an inner glass arm, 1/3 of the distance from the bottom of the tube. On the top of the glass tube there is a disc shaped electrode.

Accession Number:

Alternative Name: Crookes Tube with one mineral

Primary Materials: Wood, Metal, Glass

Markings: Old inventory number = phy75.

Dimensions (cm): Height = 25.5, Length = 9, Width = 8


A mineral fluoresces under bombardment of cathode rays. Possibly used for spectroscopy.


Associated Instruments:


Date of Manufacture:


This artifact was part of a collection of electrical instruments (mostly brass electrometers and ballistic galvanometers) gathered by University of Toronto Professor of Physics Martin J.G. Lee (d. 2009). The collection was likely acquired from Dr. Lee’s office c. 2010 or 2011.

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: