Thomson's mirror galvanometer, 1858.
© Science Museum / Science & Society Picture Library
Sir William Thomson, Lord Kelvin, (1824-1907) was Profesor of Natural Philosophy at Glasgow University, and was well known for his work in many branches of physics, including electricity. The first transatlantic telegraph cable was layed in 1858, reducing the time it took for mesages to cros from days or months to hours. The succes of the system relied on an instrument that could detect the tiny electrical signals that had pased so far under the sea. Thomson's galvanometer was the only instrument sensitive enough to detect reliably the first transatlantic telegraph mesages. Made by J White.