What is an Isochrone Map?

Once upon a time a certain Francis Galton, of Birmingham, residing in London, sat down to draw a map. It was not his first and would not be his last. It was going to be a travel map. He had published weather maps before, to be precise, the first weather maps. Galton had also published maps of the journeys of explorers that had travelled through Africa and Australia. He himself was a notable explorer and had authored books with detailed illustrations advising how other gentlemen ought to set about their explorations. The 1850s Exploration for Dummies.

He had compiled a list of cities and destinations around the world with the time it takes to travel there and thought this ought to be on a map. With London as the starting point he calculated how far one would be able to travel within 10 days. Within 20 days, 30, 40 and above that? After colouring and refining his work he named it Isochronic Passage Chart. Isochrone is Greek for ἴσο iso = same + χρόνος chronos = time.

Isochronic Passage Chart by Francis Galton 1881

The map divides the world in 10 day categories showing the days it takes to travel somewhere on the globe. Most of Europe and North African coast can be reached within 10 days from London. The North American Atlantic coast, Pacific US coast, Caribbean, Bombay and red sea within 10 to 20 days, ect… By studying the categories one can deduce that the fastest method of traveling is by ship, which overtakes land routes through Asia and brings you faster to Cape Town than Timbuktu. Also, note the two transcontinental railway links in the USA shown in slender ribbons of yellow. They enable a traveller to reach San Francisco or Vancouver faster than Santa Fe or Calgary. River travel is also important, the Nile, Amazon, Río de la Plata and Amur all have isochronic dents land inward.

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Initial spread and development of isochrone maps
The John Bartholomew and Son Map Publishing Company improved and further developed the idea and brought it to a wider audience when publishing isochrone maps in their 1889 Atlas of Commercial Geography. Albrecht Penck developed the idea further, made several improvements, defined systematic methods and published maps of countries with more details. Penck probably got a good look at a Galton isochrone map and / or visited John Bartholomew in Edinburgh in 1885 and discussed Isochrone maps there. Two years later he published a first series Isochronenkarte der österreichisch-ungarischen Monarchie in 1887.

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Based on Penck’s and a certain Franz Heiderich maps a while ago I drew an isochrone map of rail journey times in the Austro-Hungarian Empire.

Isochrone Map: Austro-Hungarian Empire Railway Network 1912

Studying this map you can see that the travel time from Vienna to Budapest is less than 6 hours, to Cracow and Prague less than 8, Zagreb 10, Trieste 12, Innsbruck 14, Lviv 16, Chernivtsi 24 and Sarajevo 26. To Zara, Spalato, Cattaro and basically all of Dalmatia it takes longer than 32 hours from Vienna or you take a ship from Trieste or Fiume.

Here some of the details.
The cities bubbles do correlate with the 1910 population census however Prague, Budapest and Vienna are shown without their suburbs otherwise Vienna would dominate even more. Note, that urbanisation was in its infancy and a large part of the population was rural. I used Color Brewer 2.0 for the categories and ran out of automatic brewed colours, thus, I brutally added shades of indigo, violet and purple at the end. Finding a text colour and format for the city labels proved difficult, I am still not quite satisfied with them. If you are into maps and Danube Monarchy history, then may I suggest Rumpler and Seger’s Die Gesellschaft der Habsburgermonarchie im Kartenbild.

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Update 10.05.2015
An earlier version of the Austro-Hungarian isochrone map mispositioned the towns Miskolc and Temesvár.

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Update 19.12.2016
adding, Franz Heiderich, (1912) Verkehrsgeographische Studien zu einer Isochronenkarte der Österreichisch-Ungarische Monarchie, Wien