..., and are sold all over Europe and South America. The plough used in this country during the colonial period was made of wood, covered with sheet-iron, the share being of wrought-iron. In 1793, Thomas Jefferson , who had been experimenting on his Virginia farm, invented an improved mouldboard, which would turn a furrow without breaking it. In 1797, Charles Newbold, of Burlington. N. J., invented a castiron...