General Information

Serial #

6771/42

Part Number

1

Total Parts

2

AKA

N/A

Patents

N/A

General Description

Metal body painted glossy black; textured black painted and brass coloured base and parts; white synthetic guide panels on angle of declination sight; metallic grey parts; clear transparent glass levels recessed and set against white background.

Dimensions

Note: These reflect the general size for storage and are not necessarily representative of the object's true dimensions.

Length

13.0 cm

Width

11.5 cm

Height

21.0 cm

Thickness

N/A

Weight

N/A

Diameter

N/A

Volume

N/A

Lexicon

Group

Astronomy

Category

Miscellaneous

Sub-Category

N/A

Manufacturer

AKA

Dominion Electric

Country

Unknown

State/Province

Unknown

City

Unknown

Context

Country

Canada

State/Province

Unknown

Period

This type of instrument probably used c. 1940s +; possibly also used earlier/later.

Canada

Unknown

Function

A navigational tool for determining the direction of north through the positions of various astronomical bodies.

Technical

An astro compass is generally a navigational tool used in aviation. In its most basic form, the astro compass consists of a base plate marked with the points of the compass, with a mechanism known as an equatorial drum mounted on it. On this drum is a set of adjustable sights and a scale of declination. More advanced versions may have built-in chronometers or default settings for bodies such as the Sun. To use the compass, the base plate is first levelled with the horizon then pointed roughly to what the user believes to be north. The equatorial drum is then tilted in relation to this base according to the local latitude. The sights are then set using the local hour angle and the declination of whatever astronomical body is being used. Once all these settings have been made, the astro compass is simply turned until the astronomical body is visible in the sights: it will then be precisely aligned to the points of the compass. Because of this procedure, an astro compass requires its user to be in possession of a nautical almanac or similar astronomical tables, one of its chief disadvantages (Ref. 1).

Area Notes

Unknown

Details

Markings

Numerous markings on instrument include: "CANADA/ ASTRO COMPASS MK. II/ REF. 6A/1174/ No. 6771/42" and "D.E.P.Co./ F.S.S.C. No. 88-C-770/ AN 5738-1" marked on circular revolving base; N. LAT. WHITE/ S. LAT RED/ ALL BEARINGS WHITE" marked on smaller revolving circle at top; "LEVEL/ SET LAT./ SET L.H.A. BODY/ ALIGN ON BODY/ READ TRUE COURSE" marked on one arm supporting smaller circle. All circles, arcs, North and South positions, etc. labelled. "GFE/ PV-1" stamped in silver ink on underside of instrument.

Missing

Appears complete.

Finish

Body painted glossy black; textured black painted and brass coloured base and parts; white synthetic guide panels on angle of declination sight; metallic grey parts; clear transparent glass levels recessed and set against white background.

Decoration

N/A