North is now generaIly credited with the invention of the milling machine-the first entirely new type of machine invented in America and the machine that, by re- placing filing, made interchangeable parts practical. In 1795, North began to produce scythes in a mill adjacent to his farm in Berlin, Conn. Four years later, he obtained a contract to make pistols and began to add a factory to the mill building. By 1813, he signed a contract to produce 20,000 pistols that specified that parts had to be completely interchangeable between any of the 20,000---the first such contract of which any such evidence exists. The first known milling machine was in use by 1818. At about that time, North was sent to John H. Hall, superintendent at Harpers Ferry (Va.) Armory, to introduce his methods of achieving interchangeability. In 1828, North received a contract to produce 5,000 Hall rifles with parts interchangeable with those produced at Harpers Ferry. North had a 53-year contractual relationship with the War Dept. The report of Charles H. Fitch prepared for the 1880 Census credits North with a key role in developing manufacture with interchangeable parts.