Astronomical Compass Mk II

Astronomy

Accession Number: 2019.ast.139 (DAA-0057)

Description:

This object is kept in a wooden box with a woven fabric handle and white lettering on the front face. Inside the box, a piece of fabric cushions the instrument; this is set over a cylindrical metal piece of unknown purpose. There is also a loose paper tag that appears to have become detached from a string tied around one leg of the instrument.

The instrument stands on a tripod of feet, two of which are adjustable. Above this there is a triangular piece and then a circular section which is graduated in 360 degrees around the rim. Sticking out from this circle there is a rectangular section inset with perpendicular horizontal levels. This reads “TRUE COURSE”. This can be turned manually, turning the whole top section of the instrument.

Above this there are several other adjustable wheels which can be altered. A small wheel that can be moved by turning a knob is labelled “LAT.” A knob wheel opposite to this turns a central horizontally mounted disks one atop the other. The bottom, graduated in red is labeled “L.H.A. SOUTH”; the top, graduate in white, “L.H.A NORTH”. On top of this there is a tilting platform with a line through the centre of it that runs to small gaps in the plastic ends. This can be tilted on a scale marked in degrees. This piece is marked “DECLINATION”.

Primary Materials: Plastic, Metal: Iron Alloy,

Markings:

Stamped on the box: “ASTRO COMPASS MK. II
REF. NO. 6A/1174
CANADA
DOMINION ELECTRIC PROTECTION COMPANY”

Written in black paint on the lid and side of the box: “102”

On a label stuck inside the lid of the box: “PACKING
Set course to South and place in box with Levels uppermost”

On the tag inside the box: “SERVICEABLE S
SECTION: 6AA REF. NO. PART NO. 220
DESCRIPTION Astro Compass
FROM 5.E.D. Stock
DATE 13 Aug 47
RCAF EE33
300M 9.45(5090)
H.Q. 885-E-33”

And on the reverse side: “REMARKS Physical Check”

Engraved on the instrument: “CANADA
ASTRO COMPASS MK II
REF. 6A/117A
D.E.P. Co.”

Dimensions (cm):

Box: Length = 25.5, Width = 14, Height = 16

Function:

This instrument uses the known position of a celestial object such as a planet or the moon, in order to locate north and thus identify the direction in which the user is traveling. It permits someone to plot a course in a situation where a magnetic compass may be unreliable (e.g. over the poles, while climbing/descending in an airplane).

Condition:

Very Good: The box of the instruments is scuffed and scratched in places. The fabric handle is frayed in places.

The instrument is in very good condition. Some of the exposed metal surfaces are slightly corroded. The declination assemblage is no longer adjustable as the bolt that holds it in place is very corroded. It otherwise functions well.

Manufacturer: Dominion Electrical Protection Company

Date of Manufacture: 1939-1947

Provenance:

This object was likely purchased as RCAF surplus sometime after WWII. This object was probably moved from the David Dunlap Observatory in Richmond Hill in 2008, upon the sale of the observatory. It was stored at the Department of Astronomy and Astrophysics until 2017, when it was moved to a new storage location in McLennan Physical Laboratories.