PREFACE. FOR thousands of years preceding the past century a forked stick was the only plow known to man with which he might till the soil; the hand sickle and the scythe were the only machines for reaping and mowing. The housewife had no sewing machine; the modern spindles and looms of our great factories were not invented. Thanks, then, to the past century for steel plows, for mowing and reaping machines, and for the application of steam and electricity! Almost all the great inventions belong to the nineteenth century, the Hercules of the Ages. With the advent of machinery, the civilizing influences of labor became more evident, and the struggle for bread and homes, for wealth and position, became sharper, and the world realizes to-day more fully than it has ever realized that not only mental, but also physical, strength and skill are essential to the success of the future citizen. In centuries past war was man's chief vocation and delight; to-day the world begins to look upon |