About the time Jefferson was working upon the mold-board, Charles Newbold, a farmer of Burlington, New Jersey, was also doing great things for the improvement of the plow. We have seen that the plow of this time was a patch work of wood and iron. Newbold thought the plow ought to be made wholly of iron and about 1796 he made one of cast iron, the point, share, and mold-board all being cast in one piece. But the New Jersey farmers did not take kindly to the iron plow. They said that iron poisoned the crops and caused weeds to grow faster than ever. So Newbold could not sell his plows and he was compelled to give up the business in despair. But soon the iron plow was to have its day. In 1819 Jethro Wood of Scipio, New York, took out a patent for a plow which was made of cast iron and which combined the best features of the plow as planned by Jefferson and by Newbold. In Wood's plow (Fig. 12) the several parts--the point, share and mold-board--were so fastened together that when one piece wore out it could easily be replaced by a new piece. In Newbold's plow when one part wore out the whole plow was rendered useless. Wood's plow became very popular and by 1825 it was rapidly driving out the half-wooden, half-iron plows of the olden time. Great improvements of course have been made upon the plow since 1819, but in the main features the best plows of to-day closely resemble the implement invented by Jethro Wood. Since our greatness as a nation is due largely to the plow all honor should be given to the memory of this inventor. "No citizen of the United States," said William H. Seward, "has conferred greater benefits on his country than Jethro Wood." [Illustration: FIG. 13.--THE GANG PLOW DRAWN BY HORSES.] [Illustration: FIG. 14.--PLOWING BY STEAM. The plow is drawn across the field by means of cables. Sometimes a traction engine moves along with the plow.] But the plow of Jethro Wood, as excellent as it was, did not fully meet the needs of the western farmer. The sod of the vast prairies could not be broken fast enough with a plow of a single share. So about the middle of the nineteenth century the _gang plow_, a hint for which had been given long before (p. 78) was invented, and as this new plow moved along three or four or five furrows were turned at once. At first the gang plow was drawn by horses (Fig. 13) but later it was drawn by steam (Fig. 14). The great gang plow drawn by steam marked the last step in the development of the plow. The forked stick drawn by human hands and making its feeble scratch on the ground had grown until it had become a mighty machine drawn across the field by an unseen force and leaving in its wake a broad belt of deeply-plowed and well-broken soil. FOOTNOTE: