NPR is running an interesting series on the NYC subway system, which turns 100 this year. They’ve got a series of soundscapes and photo galleries available online featuring scenes from the past century. Photos like this great shot of the enormous AC/DC converters used to power the cars. These things were still in use until 1999. They look like something out of Fritz Lang’s Metropolis
The New York subway was designed at the turn of the 20th century, when electric power was in its infancy. Trains were built to run on a third rail powered by Thomas Edison’s direct current technology. But just as they were coming online, George Westinghouse proved alternating current was more efficient. With miles of track ready to go, the trains needed some way of converting AC to DC. The answer came in the form of rotary converters, used for decades to change electrical power from AC to DC.