Imaginary Maps as Cartographic Guides

The Bodleian Map Room Blog looks at a specific kind of map of imaginary places, “designed to be a guide to cartographers by showing how to portray certain features, or for the map reader to show what the symbols mean.”

Here’s an example, ‘Colours and symbols used on fair sheets and fair tracing’, issued by the Hydrographic Office of the Navy in 1973. Fair here meaning a document after correction, ready to be used. But is it fair? With this ‘made-up’ map the Hydrographic Office have used real names but in random locations, so Campania, in reality a region of Italy, features, as does the English county of Rutland (though as a town here) and a made-up mountain, Montrosia. Best of all is mention of “Approaches to Valhalla”. The map shows different forms of landscape, both natural and man-made with the symbols used to show those features, and the names are added to give the whole an authentic feel.

It makes sense to do it this way: no single real map is likely to contain every single feature you’re trying to demonstrate.

La figure de la Terre

John Churchman, The magnetic atlas; or, Variation charts of the whole terraqueous globe, comprising a system of the variation and dip of the needle, by which, the observations being truly made, the longitude may be ascertained. Plate I. 1794. The Royal Society, RCN 33275.
Detail from John Churchman, The Magnetic Atlas (1794). The Royal Society, RCN 33275.

La figure de la Terre: Un débat franco-anglais (XVIIe-XXIe siècle), an exhibition running at the Bibliothèque Mazarine in Paris from 1 April to 20 June 2026.

This exhibition offers a historical and scientific journey through more than three centuries of research devoted to measuring, modeling and understanding the shape of our planet, from the 17th century through to the space age. Since ancient times, we’ve known that the Earth is, broadly speaking, a sphere. The key question was whether it was slightly flattened at the poles or elongated. To answer this question, scientists, astronomers, mathematicians and geodesists have developed theoretical models, designed innovative instruments and conducted vast observation campaigns around the world. The exhibition features exceptional sources drawn mainly from the collections of the Académie des Sciences and the Royal Society, testifying to the intensity of scientific exchanges between Paris and London and the decisive role of international cooperation in the production of knowledge.

France seems to have quite a lot of map-related programming lately.

GPS Jamming and the Iran War

GPS jamming has become pretty much endemic in every conflict, open, hybrid or frozen, so it’s no surprise that it’s going on in the Persian Gulf: “Though commercial vessels are not the target, the electronic interference disrupted the navigation systems of more than 1,100 commercial ships in UAE, Qatari, Omani and Iranian waters on February 28, according to a report from Windward, a shipping intelligence firm.” The CNN article goes on to explain why GPS (and other GNSS systems) are so vulnerable, and how spoofing and jamming have become so commonplace.

A Paris Symposium on Maps and Popular Culture

A symposium on maps and popular culture, Popcartographie : cartes et cultures populaires (XIXe-XXIe siècle), will be taking place at the Bibliothèque nationale de France’s Mitterrand site in Paris on 10-11 April 2026. Its three themes: maps in popular culture, maps as amateur practice, and the map as a paraadigm of popular fiction. Free/registration; program at the link. English translation at H-Maps. [Matthew Edney]

AI Crawlers and the Cost of Geospatial Infrastructure

Bill Dollins reacts to Gary Gale’s experience with AI crawlers taking down his mapping project (previously), and what that portends for the open geospatial web. “On its own, this is a small incident. No critical infrastructure failed. No global service collapsed. It is, however, a revealing stress case. It shows how open geospatial infrastructure behaves when exposed to a new class of demand. That demand is continuous, automated, and indifferent to the social and economic assumptions that shaped the system in the first place. This is not an isolated story. It is an early signal of a broader shift already underway.”