Menu Close



The instrument stands on a rod emerging vertically from a heavy metal tripod base, painted black. It consists of a central brass ball with two arms of different lengths emerging horizontally from the central rod. At the end of each arm, there is a vertical rod with a ball on the end; the shorter arm has a larger ball, the outer one a much smaller one. Emerging from the inner ball and running through the centre of the outer ball and out the other side for some distance is a long metal rod.

Both rods can be turned by means of a handle on the instrument’s central stand. This rotating handle is metal and turns a geared mechanism inside a metal casting on the stand. When the handle is rotated, the inner ball makes a complete rotation faster than the outer one.

Accession Number: 2019.ast.228

Alternative Name:

Primary Materials: Metal: Copper Alloy, Metal: Iron Alloy.


Handwritten on a small sticker stuck to the tripod stand: “AST45”

Dimensions (cm): Height = 49, Width = 30, Length = 120.



Very Good: The brass of the balls, arms and gear casing was enameled. This has been scratched away in places, particularly on the outer balls, rods, and on the casing of the gears. Here, the brass has dulled. The arms and rod that connects the two rotating balls are dulled across its entire length. The paint of the base appears to have been reapplied many times and is chipped in places. The metal of the stand rod is rusty across most of its surface.

The mechanism functions well. It is not clear if there are pieces missing.

Associated Instruments:


Date of Manufacture: Late 19th Century-Early 20th Century


This artifact may have been used for teaching at the Department for the Astronomy & Astrophysics or at the David Dunlap Observatory. If the former, it was probably moved at some point to the Observatory for use or storage. It was kept at the David Dunlap Observatory until 2009. Upon the sale of the Observatory, it was moved to the University of Toronto’s Department of Astronomy & Astrophysics at the St George Campus. In 2017 it was moved to a new storage location in McLennan Physical Laboratories.

Additional Information and References:

Historical Notes: