Isochronic.

Galton, Isochronic Passage Chart, 1881

Res Obscura demonstrates history through isochronic maps...

Sometimes, however, historians manage to do something truly interesting with maps.

My favorite example has long been a series of maps by the French historian Fernand Braudel, featured in his first book The Mediterranean and the Mediterranean World in the Age of Philip II. The history of the book itself is pretty fascinating in its own right: remarkably, Braudel managed to write much of it while he was in a Nazi prisoner of war camp in Lübeck, Germany, between 1942 and 1945.

Three of Braudel's maps from the book, which I've stitched together into a single GIF, brilliantly depict the time it took for a letter to reach Venice if it had been sent from a number of different cities: Moscow, Lisbon, Istanbul, and more.