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Description found in Archives
Place of creation
R. & J. Ottens
Scope and content
This chart shows the results of the first British state-sponsored expedition with a purely scientific purpose. Because the earth's magnetic field is not uniform and, as a result, the mariner's compass points either side of north to a variable degree depending on the ship's position. To make navigation safer, Halley made an extensive series of comparisons between compass readings and determinations of north by astronomical observation. He plotted isogonic lines, joining points of equal magnetic variation.
Conditions of access
Original can be viewed in the presence o
f an early cartographic archivist. Microfiche version is open.
57 Item no. assigned by LAC 57
Credit Library and Archives Canada.
Map of the world showing lines of magnetic variation.
Cartouche: Latin title, top centre, has female personifications of astronomy, navigation and geometry. Cartouche: Latin text celebrating the invention of the magnetic compass.
Inset: north pole, semi-polar azimuth projection.
Cartouches: Latin dedication to Queen Anne, English dedication to Prince George of Denmark
First published separately in 1702 by the London map publishers Mount and Page, the chart was copied by Pieter Mortier soon after, followed by the present edition by the map publishers Reinier and Josua Ottens, which they included in their 1745 edition of Louis Renard's maritime atlas and in other atlases that they assembled and sold to order in the 1730s and 1740s.
Cartographic math data
Citation / reference note
Availability of other formats note
World - Maps - Early works to 1800.
- Date modified: