Astro Compass Mark II

Astronomy

Accession Number: 2019.ast.141 (DAA-0056)

Description:

This object is kept in a wooden box, painted grey, with a woven fabric handle and white lettering on the top and 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, and a piece of wood that may have once been a support for the instrument.

The instrument stands on a tripod of feet, two of which are adjustable. Next to these there is a knurled tube attachment sticking out horizontally from the base of the instrument. Above this is a triangular piece and above that then a circular piece, mounted horizontally, 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 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 top and front of box: “DELICATE INSTRUMENT
TO BE HANDLED WITH GREAT CARE”

Also stamped on the front face: “ASTRO COMPASS Mk II”

On a paper sticker stuck to one side of the box: “Ast62A”

In chalk or white pencil on the side of the box: “12010”

On a paper sticker stuck to the inside of the lid of the box: “CAUTION
TO REMOVE COMPASS
LIFT THE COMPASS VERTICALLY UPWARDS UNTIL THE LUBBER PLATE IS CLEAR OF THE CASE
TO REPLACE COMPASS
SET SCALES AS FOLLOWS:–
TRUE BEARING AT………270
LATITUDE AT………..90
COURSE AT…….S
LOWER THE COMPASS VERTICALLY ONTO THE SUPPORTS WITH THE LUBBER PLATE DOWN”
[This has been stuck over a previous label]

On a paper tag inside the box: “SERVICEABLE
SECTION: 6AA
REF.NO. PT.NO. 220
DESCRIPTION: Astro Compass
FROM: 5.E.D. Stock
DATE: 13 Aug 47
RCAF E33
300M 9-45(5090)
H.Q. 885-E-33”

And on the reverse of this tag: “REMARKS: Physical Check R J Cork”

Engraved on the instrument:
ASTRO COMPASS MK II
REF. 6A/1174
No 186/43″
“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 that holds the instruments appears cheaply made, but is in good condition, with only a few chips and scratches in its paint surface.

The instrument is in good condition, with the exposed metal surfaces somewhat tarnished/dulled in appearance. The knobs show some signs of wear around the rims. The bolt that holds the declination component in place is corroded with white powdery corrosion.

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.