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This is a brass instrument on a circular base with three screw legs. The instrument is has a central stand which is cut open at the base to reveal a glass disc fixed flat in the base of the stand. Above this, there is a cylindrical stand with a knob enabling the rotating instrument to be fixed in place. Above this, a brass piece holds a circular rotating assembly: this has a central semi-circular piece with a graduated scale around its rim, and a long arm with a u-shaped attachment at the end. This is attached by a rod to a clockwork motor that turns the rotating piece slowly. The clockwork motor has a key to wind it up, and two switches, one that permits shifting between “A” and “R” settings.

Also attached to the central stand there is an arm that supports a rectangular mirror. This can be lengthened, and rotates smoothly around the stand; the mirror’s angle can be adjusted in any direction via a ball joint. Behind the mirror there is a round knob for adjustments. At one end of the mirror, a long rod emerges; this is intended to be fixed to the arm attached to the rotating clockwork assembly with the u-shaped attachment, but is currently free.

Accession Number: 2019.ast.133

Alternative Name:

Primary Materials:

Metal: Copper Alloy, Metal: Iron Alloy, Glass


Engraved on the circular base of the instrument: “R. FUESS

Dimensions (cm): Length = 48, Width = 18cm, Height = 31


A heliostat is designed to enable the continuous reflection of the sun’s light onto a fixed point. Clockwork drives the slow rotation of the instrument in order for it to adjust to the changing location of the sun.


Good: The surface of the instrument is somewhat tarnished and corroded around the base and the knobs attached to the base. The rod emerging from the mirror is also corroded. Many of the upper parts of the instruments are splattered by fine drops of white paint. The mirror is blackened in places around its edges, and has many fine scratches across its surface.

Some small pieces, such as the attachment to connect the mirror to the clockwork-driven arm, are missing. The glass piece in the centre of the stand is cracked across its whole width. The instrument rotates quite freely but some orientations appear jammed.

Associated Instruments:

Manufacturer: R. Fuess, Steglitz, Berlin

Date of Manufacture: 1880s


This instrument was likely acquired for astronomical work at the University of Toronto at the end of the 19th century; alternatively, it was acquired later, as an antique. It was stored at the Department of Astronomy & Astrophysics until 2017, when it was moved to a new storage location in McLennan Physical Laboratories.

Additional Information and References:

Historical Notes: