Oliver Heaviside, English physicist, c 1900.
© Science Museum / Science & Society Picture Library
Heaviside (1850-1925) was a founder of the theory of cable telegraphy. He predicted the existence of the conducting layer in the earth's upper atmosphere which allows radio waves to follow the curvature of the earth: the Heaviside layer or ionosphere. He was also a mathematician who studied the areas of vector algrebra and vector calculus and is best known for the Heaviside step function but he also was able to simplify James Maxwell's (1831-1879) 20 equations into the two that are now called Maxwell's equations.