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| 1908 poster for the train between Paris and Milan |
I'm rereading Blood of Victory by Alan Furst, a novel of espionage during WW2. Serebin, our hero, is a writer living in Paris but he's visiting Istanbul and on his return trip (page 56) he takes the Istanbul-Paris train which goes through the Simplon Tunnel. In ordinary times it would be called the Orient Express, but that service has been shut down because of the war. Not sure what's going on, it might just be literary license.
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| Various Orient Express Routes X marks the Simplon Tunnel |
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| Simplon Tunnel Profile |
The tunnel is an engineering marvel and considering when it was built it ranked as one of the great wonders of the modern world. Opened in 1906, it's 12 miles long. There is 2,000 meters of rock overhead, which means the temperature inside can get up to 130 degrees Fahrenheit.
As a rule underground is cooler in hot weather and warmer in cold weather. So how does it get up to 130°F, heat from human activity and poor ventilation?
ReplyDeleteThe geothermal gradient is defined as the increase in temperature with depth in the Earth. In normal continental crust a typical geothermal gradient within the first 3 to 5 kilometers (2 or 3 miles) of Earth's surface is about 25°C/km. , Most of the time your only a few feet to a few hundred feet underground, after that the temperature increases as you get further underground.
ReplyDeleteWell said, Mop.
ReplyDelete