The Faraday cage: from Victorian experiment to Snowden-era paranoia

Michael Faraday's pioneering work on electricity made him a 19th-century superstar. Now his signature invention is being repurposed for surveillance-proof bags, wallpaper and underpants - not to mention plot points in TV shows such as Better Call Saul

There is not much room to build a box the size of a garage in the Royal Institution's lecture theatre. Tiered seating surrounds the large central table and leaves little room for much else. It was the same in January 1836, but Michael Faraday had no choice. He left his cramped lab in the basement of the building in London's Mayfair and set to work. He put a wooden frame, 12ft square, on four glass supports and added paper walls and wire mesh. He then stepped inside and electrified it.

Faraday all but lived in the box for two full days. In that time, with electrometers, candles, and a large brass ball on a white silk thread, he explored the nature of charge. What he discovered transformed how scientists viewed electricity. But the cage itself was simply a means to an end, a way to insulate experiments from the outside world. It hardly screamed applications. Standing on the spot where the box was built, Frank James, the RI's historian, gives the simple reason: "What was there to protect against electrical charge in 1836?"