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Pointolite Bulb

Unidentified · Physics

A cardboard box containing a specialised light bulb. On all six sides of the cardboard box there are stamps “MADE IN ENGLAND”. The bulb is spherical, with a cylindrical base with a protruding pin on one side. At the tip of the bulb there is a rounded protruding glass bulb. Beneath this, in the interior of the bulb, there is a bell-shaped glass section that hangs from the top of the bulb. This is oriented over the interior apparatus of the bulb.

The interior apparatus of the bulb consists of two vertical metal posts supporting a horizontal crosspiece that ends in a coil of wire. Beneath this on its own vertical support, and not quite touching the horizontal, is a shiny metal ball about 1.5mm in diameter.

This is a bulb for an Ediswan Pointolite lamp.

Accession Number:

Alternative Name:

Primary Materials: Glass, Metal: Copper Alloy, Cardboard


On all six sides of the cardboard box there are stamps “MADE IN ENGLAND”.

Printed on the glass surface of the light bulb: “547 ROYAL EDISWAN POINTOLITE (PATENT.) MADE IN ENGLAND, 100C.P. 100V-250V”.

Dimensions (cm):

Box: Height = 15.5cm, length = 8.5cm, width = 9cm; Light Bulb: height = 12cm, Diameter = 8cm


This bulb is to be operated with a specialised “Pointolite” lamp. It is designed to emit a very bright point of light for use in experiments.


Excellent: The bulb is intact. It is not clear if the bulb is operation but no significant interior damage is visible. The horizontal crosspiece is darker at one end, suggesting heating or burning out. However, it is connected. The brass-coloured base is slightly dulled, but in very good condition. The cardboard box is dirty, has some water damage, and is very worn, but is intact.

Associated Instruments:

Manufacturer: Ediswan, England.

Date of Manufacture: 1920s-1940s


University of Toronto Department of Physics

Additional Information and References:

There are a number of examples of Pointolite lamps in the collection, under 2009,ph.24, or

Historical Notes: