understood in those early days, but all the books did not survive the numerous wars and raids of the intervening years. A book in the days of the ancients was generally about as full as a thin pamphlet or a chapter in a modern book. The author of fourteen books hardly wrote as much as the author of a ten-chapter treatise on the design of a plate girder to-day. Be this as it may, Hero is reputed to be the author of fourteen books which for some centuries were a veritable cyclopedia of engineering and of these books we have only his surveying in full, with parts of three or four other books. His treatise on surveying contains many of the problems taught to-day and his methods of solution are unchanged, except as changes have been made by the introduction of algebra and trigonometry, two subjects of which the ancients knew nothing. Hero was not regarded highly by his brother mathematicians in Alexandria because he believed in "practical, applied" mathematics and wrote books for the purpose of educating the common herd. Ile profaned a most noble science when he disclosed the grave secrets of the mathematicians and made a science of what was a philosophy. It is said that to-day the first toast at the annual banquet of a certain mathematical society is "Here's to pure mathematics. Cursed be he who attempts to find use for it."
Let us see how modern this wonderful profession of engineering is. All knowledge of stress
