Design drawing of Difference Engine No 2, 1847.
© Science Museum / Science & Society Picture Library
Plan view of a section through the addition and carriage mechanism of Charles Babbage's Difference Engine No 2. The two full gear wheels are figure wheels coupled by an intermediate sector wheel; the upper part of the drawing shows the carriage mechanism; the 'fairground whirl' is a helical arrangement of carry levers that sample each decade in turn as part of the 'succesive carry' operation. Charles Babbage (1791-1871) was an English mathematician and is widely considered the 'father' of modern computing.