Tri-centennial of a historic eclipse and map

The original 1715 map by Edmund halley with a modern reconstruction using contemporary eclipse calculations. tap to enlarge map images

300 years ago this May 3rd, a total solar eclipse passed over the British Isles and was widely seen. For the first time ever, a detailed eclipse map gave advance notice on a reasonably accurate track of the map and many in southern Britain did observe this eclipse.  (The date given on the map is April 22 1715  in the Julian calendar, which is May 3, 1715 in the modern Gregorian calendar.)

The total solar solar eclipse was the first of a series of eclipses which visited the European continent in 1715, 1724, 1737, 1748, and 1764.

The pivotal eclipse broadsides of Edmund Halley for the eclipses of 1715 and 1724 are probably the most famous early eclipse maps because they were widely available to the English public and prepared many people to successfully observe the eclipse of 1715.

In this period in Britain, a broadside was a sheet printed and sold on the streets on a subject of topical or scientific interest. Although many broadsides of Halley’s map were printed, few survive today and command high prices at auction.

Besides the new level of accuracy in eclipse predictions, there are two interesting innovations in Halley’s 1715 eclipse map. 

Click to see this map in the Houghton library collection at harvard university

Click to see this map in the Houghton library collection at harvard university

The first innovation is the umbral oval within the map that gives the map reader a picture of the umbra as a shadow intersecting the earth at a moment in time. From this oval, the map reader understands that the shadow is sweeping along the path of totality. The oval is an interesting map feature that combines the geographic context with the temporal dimension of the eclipse and gives the map a sense of dynamism.

The other innovation is Halley’s invitation for eclipse observations, shown in the text at bottom. Halley did receive reports from many parts of southern England which he applied to create a revised map with improved eclipse lines. This is akin to today’s social networking technology and makes this map participatory instead of a one-way broadcast of information.

Prof. Jay Pasachoff gives a detailed account of Halley’s maps in the Journal of Astronomical History and Heritage, 2:39:54, 1999, “Halley as an eclipse pioneer: his maps and observations of the total solar eclipses of 1715 and 1724” which can be found at A related article, "Halley and his maps of the total eclipses of 1715 and 1724" can be found at

Owen Gingerich wrote an article “Eighteen-Century Eclipse Paths” in Sky & Telescope magazine, 1981, volume 62, page 324-327. This article discusses how Halley used observations after the eclipse to produce a revised and more accurate second edition several months later. 

Halley’s post-eclipse report to the Royal Society gave his observations and summarized the reports by others. It’s a fascinating read and can be found at

I give more details on Halley's maps of 1715 and 1724 at

The essential reference for the history of British solar eclipse maps of the 18th century is The Shadow of the Moon, 1997, by Geoff Armitage, curator at the British Library. Armitage also discusses these maps at Armitage curated an exhibit of eclipse maps which is reviewed at