An isochronic map shows where to go, how long it took to get there – and what changes were on the way.
An isochronic map shows where to go, how long it took to get there – and what changes were on the way
IN 1914 JOHN G. BARTHOLOMEW, the scion of an Edinburgh mapmaking family and cartographer royal to King George V, published “An Atlas of Economic Geography”. It was a book intended for schoolboys and contained everything a thrusting young entrepreneur, imperialist, trader or traveller could need. As well as the predictable charts of rainfall, temperature and topography, it had maps showing where you could find rubber, cotton or rice; maps showing the distribution of commercial languages, so that if you wanted to do business in Indonesia you knew to do so in Dutch; and maps showing the spread of climatic diseases, so that if you did find yourself in Indonesia you knew to look out for tropical dysentery. It also contained the map you see here, which told you how long it would take to get there from London: between 20 and 30 days.This is an isochronic map – isochrones being lines joining points accessible in the same amount of time – and it tells a story about how travel was changing. You can get anywhere in the dark-pink section in the middle within five days – to the Azores in the west and the Russian city of Perm in the east. No surprises there: you’re just not going very far. Beyond that, things get a little more interesting. Within five to ten days, you can get as far as Winnipeg or the Blue Pearl of Siberia, Lake Baikal. It takes as much as 20 days to get to Tashkent, which is closer than either, or Honolulu, which is much farther away. In some places, a colour sweeps across a landmass, as pink sweeps across the eastern United States or orange across India. In others, you reach a barrier of blue not far inland, as in Africa and South America. What explains the difference? Railways.
In the early 1840s an American dry-goods merchant called Asa Whitney, who lived near New York, travelled to China on business. It took 153 days, which he thought a waste of time. When he got back he began lobbying for a transcontinental railroad connecting Lake Michigan with Oregon, which had a trade deal with China. The railroad, he thought, would cut the journey time to China to about 30 days and open up the market. Similarly, the British invested so heavily in the Indian railway that between 1860 and 1880 it extended from 838 miles to 15,842 miles. If you compare this isochronic map to one from the 1870s, by Francis Galton, you see the difference. Bombay is quickly accessible by sea; the rest of India less so. Likewise, there is no spit of pink reaching across the Russian Empire on Galton’s map, because there was no Trans-Siberian Railway. As the geographer L.W. Lyde says in his introduction to Bartholomew’s atlas, “isochronic distances…change with every additional mile of railway brought into use.” What was the one thing a young entrepreneur needed most? A train ticket. ~ SIMON WILLIS
Source: Time travel | Intelligent Life magazine