Little further improvement was made in the printing press before the year 1798, when the Earl of Stanhope caused one to be made, the frame of which, instead of being of wood, was one piece of cast-iron. A necessity had arisen for greater power in giving the impression, especially in the printing of woodcuts, and the tendency was naturally toward larger forms of type, requiring greater exertion on the part of the printer; the labor in working one of the old screw presses was about equal to that of the plowman in the field. The Earl of Stanhope reserved the screw, but caused to be added a combination of levers to assist the pressman in gaining greater power, when giving the impression, with less expenditure of energy. These machines were very heavy and extremely cumbersome. They were the first iron printing presses ever constructed, and came into use to some extent. The printers, seizing upon this new idea of a combination of levers to increase the power, were induced to place them upon their wooden presses, the improvement resulting generally in the destruction of the latter, which were not adapted to stand the strain. The iron platen employed by the Earl of Stanhope had, however, previously been used upon the wooden presses. [Illustration: CLYMER’S COLUMBIAN PRESS] The next practical improvement was made by George Clymer of Philadelphia, who, about 1816, devised an iron machine, entirely dispensing with a screw. A long, heavy cast-iron lever was placed over the platen, one end attached to one of the uprights of the cast-iron frame, and the other susceptible of being raised and lowered by a combination of smaller levers, worked by the pressman after the manner of the ordinary hand press. The impression was given and the platen raised and lowered by a spindle, or pin, attached to the centre of the large cross lever at the top, this being properly balanced to facilitate its being raised with greater ease. Mr. Clymer carried his invention to England, where it was introduced to some extent and was known as the “Columbian” press. [Illustration: PETER SMITH HAND PRESS] In England there were iron hand presses made by Rutheven, by Brown and by others, all, more or less, improvements upon the Stanhope. In 1822 Peter Smith, an American, connected with the firm of R. Hoe & Co. in New York, devised a machine which was in many respects superior to any up to that time. The frame was of cast-iron, and in place of the screw with levers, he substituted a toggle joint, at once simple and effective.