"Probably the most rapid development of an industry that the world has ever seen," says Mr. Carnegie, "is that of Bessemer steel in America." In 1870 America made 40,000 tons of Bessemer; in 1885, fifteen years later, she made 1,373,513 tons, which was 74,000 tons more than Great Britain made. "This is advancing not by leaps and bounds, it is one grand rush--a rush without pause, which has made America the greatest manufacturer of Bessemer steel in the world.... One is startled to find that more yards of carpet are manufactured in and around the city of Philadelphia alone than in the whole of Great Britain. It is not twenty years since the American imported his carpets, and now he makes more at one point than the greatest European manufacturing nation does in all its territory." Of the manufacture of boots and shoes by machinery, Mr. Carnegie says, "A man can make three hundred pairs of boots in a day, and a single factory in Massachusetts turns out as many pairs yearly as thirty-two thousand bootmakers in Paris.... Twenty-five years ago the American conceived the idea of making watches by machinery upon a gigantic scale. The principal establishment made only five watches per day as late as 1854. Now thirteen hundred per day is the daily task, and six thousand watches per month are sent to the London agency." The progress in mining has been equally remarkable. "To the world's stock of gold," says Mr. Carnegie, "America has contributed, according to Mulhall, more than fifty per cent. In 1880 he estimated the amount of gold in the world at 10,355 tons, worth $7,240,000,000. Of this the New World contributed 5,302 tons, or more than half. One of the most remarkable veins of metal known is the Comstock Lode in Nevada.... In fourteen years this single vein yielded $180,000,000. In one year, 1876, the product of the lode was $18,000,000 in gold, and $20,500,000 in silver,--a total of $38,500,000. Here, again, is something which the world never saw before. "America also leads the world in copper, the United States and Chili contributing nearly one-half the world's supply.... On the south shore of Lake Superior this metal is found almost pure, in masses of all sizes, up to many tons in weight. It was used by the native Indians, and traces of their rude mining operations are still visible." Mr. Carnegie says the anthracite coal-fields of Pennsylvania will produce 30,000,000 tons per year for four hundred and thirty-nine years; and he thinks by that time "men will probably be burning the hydrogen of water, or be fully utilizing the solar rays or the tidal energy." The coal area of the United States comprises 300,000 square miles; and Mr. Carnegie "is almost ashamed to confess it, she has three-quarters of all the coal area of the earth."