first efforts to apply science to agriculture were made. During this period, as in the first one, agriculture was practically self-sufficing, though in the South the specialization on cotton caused a considerable dependence on other regions for supplies that otherwise would have been produced at home.
In the third period, from 1830 to 1865, occurred an almost complete transformation of agriculture. The rapid rise of the factory system in the North, due to the use of steam and a flood of labor saving inventions with a consequent transfer of home industries into the shops, the invention of agricultural machinery such as the reaper, mower, thresher, etc., the extension of the railway system and the development of the prairie states caused an era of specialization which transferred agriculture into the commercial stage. Crops were now grown primarily for the market and incidentally for the use of the farmer and his family, a reversal of the former process. The new necessities of the farmer gave him a new view of his industry and in his effort to meet the new situation he turned to agricultural societies, fair associations and the scientific breeding of live stock, all of which were of wonderful assistance in the development of the country by demonstrating its resourcefulness.
The fourth period was the era of expansion into the Far West (1865–1887), and was remarkably stimulated by the Homestead Acts of 1862 and 1864, the disbanding of the Armies of the Civil War, the transformation of Southern farming due to the abolition of slavery, the invention of the twine binder and the roller process of milling flour, the exten-
