Rare, reduced version of the first chart to show the pattern of magnetic variation

Description

From 1676 to 1678, English polymath Edmond Halley undertook an expedition to the island of Saint Helena, primarily to carry out astronomical observations. The expedition also yielded the first chart to depict trade winds and monsoons. Halley published it in 1686.

Between 1698 and 1700, Halley completed two scientific voyages to the Atlantic by order of King William III. The first of these was the first purely scientific voyage by an English naval vessel. One of the main purposes of these expeditions was to study extensively terrestrial magnetism, including compass variation, also known as magnetic variation or declination. Halley published his findings in 1701, in the General Chart of the Variation of the Compass, using dedicated lines to show the pattern of magnetic variation. Featuring what more than a century later started being referred to as isogonic lines, this was the first chart of its kind. In 1702, Halley extended it to show magnetic variation in the Indian Ocean.

The chart at hand, published between 1705 and 1708, is a reduced version of the chart published in 1701/1702. It is unique in that it combines the information contained in all earlier charts mentioned – trade winds and monsoons as well as magnetic variation for both the Atlantic as well as the Indian Ocean.

Trade winds are depicted primarily between the tropics of Cancer and Capricorn. Monsoons are annotated with month of occurrence. Magnetic variation is shown through single as well as dashed isogonic lines, with double lines indicating locations of no variation.

The arrow symbols Halley used to represent prevailing winds have continued being in use in cartography and meteorology to this day. His magnetic variation lines inspired later similar use of lines for data and information visualisation, as seen in isotherms and isobars, for example.

Further notable features of the chart include:

• California as an island
• Great Lakes not shown
• New Guinea connected to Australia
• incomplete coastlines for northwestern North America, northeastern Asia, eastern Australia, and Tasmania
• in New Zealand’s place, only Manawatāwhi / the Three Kings Island(s), located northwest of the New Zealand mainland, shown.

Other hallmarks encompass:

• prime meridian shown at 20°W, with more subtle indication of “Meridian of London” as well
• annotations mentioning years of first sighting of various territories by Europeans
• an inset map of the North Pole on the lower left
• a boxed note, also on lower left, advertising the sale of Halley’s larger two-sheet map of the world by Richard Mount and Thomas Page on Great Tower Hill, London.

Engraved by John Harris, who also engraved Halley’s earlier, larger map.

A rare, unusual, and important map, contributing to the emergence of thematic maps and inspiring their continued development.

Publication

Miscellanea curiosa : being a collection of some of the principal phaenomena in nature, accounted for by the greatest philosophers of this age : together with several discourses read before the Royal Society for the advancement of physical and mathematical knowledge … [First edition, 1705-1707]

[OR]

Miscellanea curiosa : containing a collection of some of the principal phaenomena in nature, accounted for by the greatest philosophers of this age : being the most valuable discourses, read and delivered to the Royal Society, for the advancement of physical and mathematical knowledge … [Second and third editions, 1708]

Note: Image shows pagination annotation ([Vo]l. I. Plate 2 pag. 61.] in top left corner.

Condition

Good.

Issued folding and now flattened. Professionally cleaned and chemically stabilised, with minor soiling along bottom neatline remaining. Professionally remargined at top, bottom, left, and lower right corner, to compensate for minute missing sections of neatline at lower right and bottom left, and to allow for framing. Verso clean.

Item #: 00896

US $480.00

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