The first satisfactory calculating machine of this nature was that of C. X. Thomas, which was brought out about 1820. It is usually called the Thomas de Colmar Arithmometer. This Thomas type of machine, which is commonly known as the beveled gear type, is still in use today in modern business. The “Difference Engine.” In the year 1822 a very ambitious project was conceived by Charles Babbage. He commenced to construct an automatic calculating machine, which he called a “difference engine.” The work was continued during the following twenty years, the English government contributing about $85,000 to defray its cost. Babbage himself spent a further sum of about $30,000. At the end of that time the construction of the engine, though nearly finished, was unfortunately abandoned, owing to some misunderstanding with the government. A portion of this engine is exhibited in South Kensington Museum, London, along with other examples of Babbage’s work. If the engine had been finished it would have contained seven columns of wheels, twenty wheels in each column, and also a contrivance for stereotyping the tables calculated by it. It was intended to perform the most extended calculations required in astronomy and navigation, and to stamp a record of its work into plates of copper or other material. [Illustration: CHARLES BABBAGE’S “ENGINE OF DIFFERENCES” WAS THE FIRST ADDING MACHINE INVENTED WHICH WAS DESIGNED TO PRINT A RECORD OF ITS WORK, BUT IT WAS NOT A SUCCESS _Courtesy of the Burroughs Adding Machine Company._] Babbage began to design his “analytical engine” in 1833 and he put together a small portion of it shortly before his death in 1871. This engine was to be capable of evaluating any algebraic formula. The formula it is desired to evaluate would be communicated to the engine by two sets of perforated cards similar to those used in the Jacquard loom. These cards would cause the engine automatically to operate on the numerical data placed in it, in such a way as to produce the correct result. Notwithstanding its simple action, its structure is complicated by a large amount of adding mechanism. A complete set of adding wheels with carrying gear being required for the tabular number, and every order of difference except the highest order. After Babbage, there was much experimenting done by inventors to produce a real adding and listing machine. Also inspired by Babbage’s work Scheutz of Stockholm made a “difference engine,” which was exhibited in England in 1864, and subsequently acquired for Dudley Observatory, Albany, N. Y. Scheutz’s engine had mechanism for calculating with four orders of differences of sixteen figures each. As far as we know the first patent in this country issued by the patent office for a calculating machine was to O. L. Castle of Alton, Illinois, in 1850. It was for a ten-key adding machine which did not print and only added in one column. Work on Some of the Present-Day Models.