Menu Close

Cathode Ray Tube with Five Minerals


A 26 cm glass bulb mounted on a wooden collar stemming from a wooden base. The bottom half of the bulb is narrow, 7 cm in diameter, and the top half is spherical, coming to a point with a metal (copper?) cover on top. Halfway up the first, narrow part of the bulb is a short, 5 cm projection with an electrode in it. Inside the large bulb are five different minerals secured in glass fixtures.

Accession Number:

Alternative Name: Crookes tube; Fluorescing tube

Primary Materials: Metal, Wood, Glass

Markings: Old Inventory Number = phy76

Dimensions (cm):

Height = 35, Base Diameter = 14, Bulb Diameter = 14


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


Associated Instruments:


Date of Manufacture:


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:

Likely built by Richard Muller-Uri (Braunschweig)