Next in importance comes the production of iron and steel. Steel, on account of its great cost and brittleness, was only used for tools and special purposes until past the middle of the last century. This has been all changed by the invention of his steel by Bessemer in 1864, and open-hearth steel in the furnace of Siemens, perfected some twenty years since by Gilchrist & Thomas. The United States have taken the lead in steel manufacture. In 1873 Great Britain made three times as much steel as the United States. Now the United States makes twice as much as Great Britain, or forty per cent. of all the steel made in the world. Mr. Carnegie has explained the reason why, in epigrammatic phrase: “Three pounds of steel billets can be sold for two cents.” This stimulates rail and water traffic and other industries, as he tells us one pound of steel requires two pounds of ore, one and one-third pounds of coal, and one-third of a pound of limestone. It is not surprising, therefore, that the States bordering on the lakes have created a traffic of 25,000,000 tons yearly through the Sault Ste. Marie Canal, while the Suez, which supplies the wants of half the population of the world, has only 7,000,000, or less than the tonnage of the little Harlem River at New York. INDUSTRIAL ENGINEERING This leads us to our last topic, for which too little room has been left. Industrial engineering covers statical, hydraulic, mechanical, and electrical engineering, and adds a new branch which we may call chemical engineering. This is pre-eminently a child of the nineteenth century, and is the conversion of one thing into another by a knowledge of their chemical constituents. When Dalton first applied mathematics to chemistry and made it quantitative, he gave the key which led to the discoveries of Cavendish, Gay-Lussac, Berzelius, Liebig, and others. This new knowledge was not locked up, but at once given to the world, and made use of. Its first application on a large scale was made by Napoleon in encouraging the manufacture of sugar from beets. The new products were generally made from what were called “waste material.” We now have the manufacture of soda, bleaching powders, aniline dyes, and other products of the distillation of coal, also coal-oil from petroleum (known fifty or sixty years ago only as a horse medicine), acetylene gas, celluloid, rubber goods in all their numerous varieties, high explosives, cement, artificial manures, artificial ice, beet-sugar, and even beer may now be included. Through many ages, the alchemists, groping in the dark, and in ignorance of nature’s laws, wasted their time in trying to find what they called the philosopher’s stone, which they hoped would transform the baser metals into gold. If such a thing could be found it would be a curse, as it would take away one of the most useful instruments we have—a fixed standard of value.