A Chart of Magnetic Curves of Equal Variation.
1851 (undated) 11.5 x 17 in (29.21 x 43.18 cm)
A fine example of Adam and Charles Black's 1851 chart of the World's Magnetic Curves. The chart depicts the magnetic curves over the entire world, but does not show the isomagnetic lines over any continent except North America. It marks the northern magnetic pole at the Boothia Felix (now the Boothia Peninsula) based on the first expedition by James Clark Ross in 1831. Due to the magnetic changes in the earth's core, the position of the magnetic poles change over time. In 2005, it was estimated that the northern magnetic pole was positioned to the west of ellesmere Island in Canada. Throughout, the map identifies various cities, rivers and an assortment of additional topographical details. It names various countries, but no boundaries are depicted. The map is engraved by G. Aikman and issued as plate no. III-I in the 1851 edition of Black's General Atlas.
Charles and Adam Black (fl. 1807 - present) were map and book publishers based in Edinburgh. Charles and his uncle, Adam, both of Edinburgh, Scotland, founded their publishing firm in 1807. They published a series of maps and atlases throughout the 19th century. In addition to an array of atlases, the Black firm is known for their editions of the Encyclopedia Britannica (1817 - 1826) and the first publishing of Sir Walter Scott's novels in 1854. In 1889 the A. & C. Black publishing house moved to London where it remains in operation to this day.
Black, A. and C., General Atlas Of The World, (Edinburgh) 1851.
Very good. Blank on verso. Original platemark visible.
Rumsey 2305.006 (1854 edition). Philips (atlases) 4334.