Engraving of Charles Babbage's Difference Engine No. 1. Begun in 1823, a portion was completed in 1833 & the project abandoned in 1842. This portion is in the Science Museum in London. It consists of three columns, each of six cages. The first five cages in the right column, or the table column, can be set by hand. The middle column or the first difference column, & the second difference column (left), have five cages that can be set. The lowest cage represents units, the next tens, & so on. Any number up to 99, 999 can be set in the table column. Once the difference column is set & the handle turned the machine adds the difference to the table column.