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 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, varnished with a reddish varnish, and a central support spire. Into this, a narrow base point of the glass tube is inserted, cushioned by a piece of cork cut with a hole.
Accession Number: 2009.ph.105
Alternative Name: Crookes Tube with Maltese Cross
Metal: Platinum?, Metal: Unknown, Glass, Wood, Wood: Cork
On the base on a gold transfer sticker: “MADE IN WESTERN GERMANY”
Marked by hand beneath this, in white ink or paint: “1142A”.
Dimensions (cm): Height = 26.5, Length = 32, Width = 12
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 where the varnish has been scratched off, and has a significant split from one side of its rim about 2/3 of the way towards the central support spire.
Associated Instruments:
Manufacturer: Made in Western Germany.
Date of Manufacture: 20th Century
University of Toronto Department of Physics
Additional Information and References:
Historical Notes: