Henry Babbage's Analytical Engine Mill, 1910.

Henry Provost Babbage was the youngest son of Charles Babbage (1791-1871), the English computer pioneer. After his father's death, Henry built a hand-operated printing calculator, based on the plans for the mill of his father's Analytical Engine. It was a four-function calulator designed for addition, subtraction, multiplication and division. Henry also asembled approximately six small demonstration models of the calulating mechanisms of the Difference Engine No 1.