General Information

Serial #

N/A

Part Number

1

Total Parts

1

AKA

N/A

Patents

N/A

General Description

Mahogany octant has boxwood scale; brass & glass fittings, ivory inset in frame & over scale/ mahogany (?) case

Dimensions

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

Length

52.0 cm

Width

47.8 cm

Height

9.1 cm

Thickness

N/A

Weight

N/A

Diameter

N/A

Volume

N/A

Lexicon

Group

Exploration and Survey

Category

Measurement-angles

Sub-Category

N/A

Manufacturer

AKA

Cole

Country

England

State/Province

Unknown

City

London

Context

Country

Worldwide

State/Province

Unknown

Period

Probably used c. 1760-1850

Canada

Unknown. G.C. Morrison, Glenholme Nova Scotia is written in pencil on the inside of the cover. Manufactured by Benjamin Cole Jr., of London. Bought from Christie's Auction.

Function

To determine latitude, by measuring the altitude of heavenly bodies above the horizon. Large radius octant. Navigators at sea could determine latitude and longitude by measuring the angle between celestial objects and the horizon line. This angle was measured by adjusting the scale until the celestial object appeared to touch the horizon line in a mirror.

Technical

Example of large radius octant with transversal type scale. It represents quality instrument, made by well-known mfr., in transition period between large radius octants divided by hand & those divided by machine & of small radius (ref.1).superseded in 1770s by more accurate sextant, octant made & used c.1900 because it was less expensive to produce (ref.3, p.264). Double "pin-hole" sight and back sight. Example of large radius octant with a transversal type scale. Numbers are on both sides of the scale and go from 0? to 90? on one side in 2 minute intervals and the opposite direction on the other side in 20 minute intervals. It represents a quality instrument in the transition period between large radius octants divided by hand and those divided by ruling engines.

Area Notes

Unknown

Details

Markings

'COLE Maker/ Fleet Street/ LONDON' INCISED & HIGHLIGHTED IN BLACK ON LEFT END OF SCALE ON ARC. SCALE DIVIDED 0-90 BY 2-MINUTE INTERVALS ON TOP EDGE; 90-0 BY 20-MINUTE INTERVALS ON LOWER EDGE/ 'G C Morrison/ Glenholm/ N.S.' HANDWRITTEN IN PENCIL ON INSIDE OF CASE LID/ CHRISTIE'S LABEL ON LOWER FRONT EDGE OF CASE READS: '312/ 8 JUNE 1992'.

Missing

None

Finish

Unknown

Decoration

N/A