A tapering glass cylinder is mounted horizontally on a turned wood base. Electrodes mounted in glass tubes project from the narrow end and base of the glass cylinder. A hinged Maltese cross shape made of silver metal sits at the broad end of the glass cylinder, supported by a glass arm; this cross is hinged so it can be flapped up to stand vertically, or lie down.
The wooden base consists of a circular broad base, light coloured, and a central support spire. Into this, a narrow base point of the glass tube is inserted, cushioned by a piece of red rubber.
Accession Number: 2009.ph.136
Alternative Name: Crookes Tube with Maltese Cross
Metal: Platinum?, Metal: Unknown, Glass, Wood, Wood: Cork
Markings: Old inventory number = phy27.
Height = 26.5, Width = 12.5, Length = 32.5
This Cathode Ray Tube demonstrates the path of cathode rays (electrons) using fluorescence. The metal cross blocks the rays, leaving a cross-shaped shadow in fluorescence appearing on the glass behind. When the cross is lowered, the formerly shadowed mark glows brighter than the surrounding glass. This instrument was likely used to demonstrate this feature to undergraduates.
Very Good: The glass tube and internal components is intact and shows little sign of discolouration. The wooden base is marked in places and appears to have some faint water damage around one side of its rim.
Date of Manufacture: Early-Mid. 20th Cent.
Department of Physics, University of Toronto
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