Letters: Colossal enigma

Sir: Your article on the origins of the computer (8 July) is headed by an incorrectly captioned photograph, purporting to show a Colossus, an early computer built at Bletchley Park in 1943.

The Colossus was over 2m high and 3m long, and weighed a tonne. What your photograph shows is an enigma machine, a portable German electromechanical coding machine (only about 34 x 28 x 15cm), widely used by the Germans during the last war. Colossus was built specifically to aid in the decrypting of Lorenz messages, which were based on a more sophisticated system than Enigma.

Dr MARK BALDWIN

Cleobury Mortimer,

Worcestershire