• Title : Published by the Society for the Diffusion of Useful Knowledge
• Size: 16in x 14in (410mm x 355m)
• Condition: (A+) Fine Condition
• Date : 1840
• Ref #:  24676-1

Description:
This hand coloured original steel-plate engraved antique Gnomonic Map of eastern Australia, New Zealand & The South Pacific was engraved by J & C Walker, in 1840 and was published in the Chapman & Hall edition of the Society For the Diffusion of Useful Knowledge (SDUK) Atlas.

A gnomonic map projection displays all great circles as straight lines, resulting in any line segment on a gnomonic map showing a geodesic, the shortest route between the segment\'s two endpoints. This is achieved by casting surface points of the sphere onto a tangent plane, each landing where a ray from the center of the sphere passes through the point on the surface and then on to the plane. No distortion occurs at the tangent point, but distortion increases rapidly away from it. Less than half of the sphere can be projected onto a finite map. Consequently a rectilinear photographic lens cannot image more than 180 degrees.

General Definitions:
Paper thickness and quality: - Heavy and stable
Paper color : - off white
Age of map color: - Original
Colors used: - Yellow, pink, green, blue
General color appearance: - Authentic
Paper size: - 16in x 14in (410mm x 355m)
Plate size: - 16in x 14in (410mm x 355m)
Margins: - Min 1/4in (5mm)

Imperfections:
Margins: - Light age toning
Plate area: - None
Verso: - None

Background: 
The SDUK produced two landmark volumes of cartography in the first half of the 19th century. The first volume concentrated on areas of the old world, Europe, Africa, Great Britain etc. The second volume contained maps of the new world, America, South Asia, including US state maps, colonies of Australia, South Africa, South America etc. Also included were some of the finest engraved town and city plans published at that time.
The SDUK was published in its entirety or in part by many publishers including Baldwin and Cradock 1829-32, Chapman & Hall in 1844, Charles Knight & co. 1846 – 1852. G. Cox published the SDUK between 1852-3, Stanford 1857-70 and later revised edition were also published after Stanford. (Ref: Tooley, M&B)