Sextant

Astronomy

Accession Number: 2012.ast.2

Description:

This is a sextant with four telescope/optical attachments in a fan shaped wooden box. The box is hinged on one of the sides. The sextant is stored flat in the box, with the handle facing downwards, and the additional components stored underneath. A block of wood affixed to the lid holds the sextant in place when the lid is closed.

The sextant is made of brass, painted black with a wooden handle underneath it. It is triangular, with an unpainted graduated arc on one side (the lower side when in use). There is a mirror, ring mount for telescope attachments, and filters above, on the straight sides. The ring mount has an adjusting brass knob and grooves for telescope attachments. The mirror is adjacent to the ring mount, faces away from ring mount (if the sextant is held in the right hand) and is slightly cracked.

Adjacent to the mirror are four coloured glass filters for reflected light from the mirror. Adjacent to the filters is mounted an oval glass piece, split in two. One half is a mirror angled to reflect light from the primary mirror to the ring mount. The other half is clear to allow direct observation through a telescope attachment on the ring mount. Adjacent to the split oval lens are 3 more coloured glass filters for direct light from a distant observation.

The graduated arc covers roughly 60 degrees and is labeled from 5 to 0 to 145. Finely inscribed increments between these numbers may be read using a magnifying glass attached to the measuring arm of the sextant. The measuring arm moves along the graduated arc as the top mirror is adjusted and has a movable Vernier marked from 0 to 10.

Three of the telescope attachments are threaded to fit into the ring mount; the fourth is a loose component lens. The telescope attachments vary in length and lens aperture.

Alternative Name:

Primary Materials:

Sextant and parts: Brass (painted black and open), glass and wood. Box: wood, iron (nails and hinges), woven fabric.

Markings:

Engraved on graduated arc: “Troughton & Simms, London”

Printed on label on inside of box: “RIGGS & BROTHER. Transit Observa… Established in 1820. Successors to W. B. C. Riggs. 244 So. Front near Dock, Philadelphia. Chronometers. Clocks. Watches. Nautical Instruments. Books. Charts. &c. N.B. All kinds of Nautical Instruments Repaired.”

Handwritten in pencil on inside lid: “U. of Toronto”.

Dimensions (cm):

Box: Length = 34, Width = 26.5, Height = 13.5

Function:

A sextant is for measuring angles between distant objects. It is used in navigation, astronomy and surveying. This one was likely purchased for teaching these skills to students. .

Condition:

Good: The box is intact, but worn across its surface with marks and dents. The joints are coming away from each other. There is a large crack across its bottom. There is some insect damage on the label on the interior of the lid, particularly around the top and bottom where it was affixed to the wood.

The instrument is in good condition. There is some tarnishing on graduated arc – fingerprints, and the black paint is chipped across the whole instrument. The mirror is slightly cracked and the glass filters are scratched. The handle has split through the centre, around where there is a nail through the centre of the handle.

Associated Instruments: 2011.ast.1, 2012.ast.3

Manufacturer: Troughton & Simms, London

Date of Manufacture: Mid 1800s

Provenance:

This artifact was likely 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 storage. The sphere 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.