Next to the great social transformation caused by these modern means of fighting isolation comes the emancipation from drudgery brought in by farm machinery. Labor saving machinery is just as much a feature of modern civilization in the country as it is in the city. Machinery, by developing the factory system, centralized industry and produced the great cities, attracting thousands from the farms to man the looms. But this is only half the story. Meanwhile the invention of _agricultural_ machinery made it possible for the farm work of the country to be done by fewer men. Therefore the farm population of the United States decreased from 47.6% in 1870 to 35.7% in 1900, representing a change from agriculture to other employments by three and a half millions of people. Meanwhile, comparing the average value of farms, and the relative purchasing power of money, the average farmer was 42% better off at the end of the century than fifty years before.[16] The tendency of farm machinery to throw men out of employment and send many to the city is shown by these facts from the thirteenth annual report of the U. S. Commissioner of Labor. The sowing of small grains is accomplished nowadays by machine methods in from one-fifth to one-fourth the time formerly required for hand-sowing. One man with a modern harvester can now do the work of eight men using the old methods, while the modern threshing machine has displaced fourteen to twenty-nine farm laborers. Machinery displaces the labor or increases the crop, according to circumstances; but usually both. It has greatly increased the output of farm products, sometimes reduced prices, and vastly increased the efficiency of the workers. Of nine of the more important crops, the average increase in labor efficiency in the past two generations has been 500%, while in the case of barley it was over 2,200%, and nearly the same for wheat.[17] _The Evolution of Farm Machinery_ The great incentive in America for our astonishing development of farm machinery has been our cheap lands and our relatively high wages. But the noble desire to rise above the slavery of drudgery has constantly had its influence. American ambition has combined with Yankee ingenuity to produce this wonderful story. The plow, that greatest of all implements, has passed through constant changes, from the crude simplicity of early days to the giant steam gang-plow of the present. The first steel plow was made in 1837 from an old saw blade! The first mowing machine was patented in 1831. Imperfect reapers appeared two years later and were made practicable by 1840, one of the triumphs of modern industry. Meanwhile threshing machines began to come into use and separaters were combined with them by 1850. The first steam thresher appeared in 1860.