He died in New York City, July 15, 1868, and was buried in Mount Auburn Cemetery, Cambridge, Massachusetts, perhaps the most beautiful and illustrious of American burial places. The monument of Dr. Morton in Mount Auburn bears this inscription: "William T. G. Morton, inventor and revealer of anæsthetic inhalation, by whom pain in surgery was averted and annulled; before whom, in all time, surgery was agony; since whom, science has control of pain." He is included among the fifty-three illustrious sons of Massachusetts whose names are inscribed upon the dome of the new Hall of Representatives in the State House at Boston; and is among the five hundred noted men whose names adorn the facade of the Boston Public Library. The news of Morton's discovery reached England December 17, 1846. Within five days ether was in use as an anæsthetic by the English dentists and surgeons. A year later Sir J. Y. Simpson, of Edinburgh discovered the anæsthetic properties of chloroform, which has since that time been the preferred anæsthetic in Europe. Ether has continued in general use in America. CHAPTER XI STEEL AND RUBBER It has been shown already in this volume that the materials from which man has made his tools, and those tools themselves, are the best means of determining his advance in civilization. Man passed from the Stone Age with its few, crude implements into the Bronze Age, and from this into the Iron Age, with each succeeding step increasing the number and efficiency of his tools. The race has lately passed into an age which might well be named the Age of Steel. The discovery or invention of this metal--for there is in it the nature of both invention and discovery--is sufficiently important to mark a distinct era in human progress. Steel is not found native, but is a compound of iron and carbon and is produced artificially. The great value of steel lies in the fact that it can be made so hard that it can cut and shape almost every other substance known to man, and yet this very quality of hardness can be so modified as to make the metal capable of cutting and otherwise shaping itself. Steel can be made nearly as hard as the diamond, or so soft that it can be cut, bent, or hammered into this shape or that, rolled into sheets, or drawn out into the finest wire. Nearly the whole of the compound is iron, the carbon ranging from one-fourth of one per cent to two and one half per cent. Ordinary steel contains certain other chemicals, such as silicon, manganese, sulphur, and phosphorus, but these are mere natural impurities existing in the metal. The essential ingredients are iron and carbon. Steel is hardened by being heated to a high temperature and then suddenly cooled by contact with cold water, or in other like ways. Fixing the degree of hardness in a piece of steel is called tempering. The degree of hardness is dependent upon the suddenness of cooling.