Charles Babbage (1791-1871) was an English mathematician, inventor, and mechanical engineer best known for designing two calculating machines: the Difference Engine and the Analytical Engine. He spent much of his life trying to build machines that could replace error-prone human computation of mathematical tables.
The Difference Engine was designed to calculate and tabulate polynomial functions automatically using the method of finite differences. In his autobiography, “Passages from the Life of a Philosopher” (1864), Babbage describes its arithmetic as resting on “the power of adding one digit to another, and also of carrying the tens to the next digit.” A full version of the first Difference Engine was never completed in his lifetime.
His more ambitious design, the Analytical Engine, is described in Chapter VIII of the same book, titled “Of the Analytical Engine.” Unlike the Difference Engine, it was intended to be general-purpose: it separated a “store” for holding numbers from a “mill” for performing operations, and it was to be controlled by punched cards in the manner of the Jacquard loom. This separation of memory and processing, together with conditional control, makes the design an early ancestor of the modern computer.
Babbage’s collaboration with Ada Lovelace, who translated and extensively annotated Menabrea’s account of the Analytical Engine, helped record and explain the machine’s potential. Neither the Analytical Engine nor the full Difference Engine was finished while Babbage lived, but his designs were studied long afterward as foundational work in the history of computing.