Page:Popular Science Monthly Volume 8.djvu/44

34 Rapid as has been the growth of the art of the engineer during the last century, we must, if we would trace its origin, seek among the earliest evidences of civilization. When settled communities were few and isolated, opportunities for the interchange of knowledge were scanty or wanting. The slowly accumulated results of the experience of a community were lost on its downfall. Inventions were lost and found again. The art of casting bronze over iron was known to the Assyrians, though it has only lately been introduced into modern metallurgy; and patents were granted in 1609 for processes connected with the manufacture of glass, which had been practised centuries before. An inventor in the reign of Tiberius devised a method of producing flexible glass, but the manufactory of the artist was totally destroyed in order to prevent the manufacture of copper, silver, and gold, from becoming depreciated.

In the long discussion which was held as to the practicability of making the Suez Canal, an early objection was brought against it that there was a difference of thirty-two and one-half feet between the level of the Red Sea and that of the Mediterranean. Laplace declared that such could not be the case, for the mean level of the sea was the same on all parts of the globe. Centuries before the time of Laplace the same objection had been raised against a project for joining the waters of these two seas. According to the old Greek and Roman historians, it was a fear of flooding Egypt with the waters of the Red Sea that made Darius, and in later times again Ptolemy, hesitate to open the canal between Suez and the Nile. Yet this canal was made and was in use some centuries before the time of Darius. Strabo tells us that the same objection, that the adjoining seas were of different levels, was made by his engineers to Demetrius, who wished to cut a canal through the Isthmus of Corinth some two thousand years ago. But Strabo dismisses at once this idea of a difference of level, agreeing with Archimedes that the force of gravity spreads the sea equally over the earth.

When knowledge in its higher branches was confined to a few, those who possessed it were called upon to perform various services for the communities to which they belonged; and we find mathematicians, and astronomers, painters, sculptors, and priests, called upon to perform the duties which now pertain to the profession of the architect and the engineer. As soon as civilization had advanced so far as to admit of the accumulation of wealth and power, then kings and rulers sought to add to their glory while living by the erection of magnificent dwelling-places, and to provide for their aggrandizement after death by the construction of costly tombs and temples.

The earliest buildings of stone to which we can assign a date, with any approach to accuracy, are the pyramids of Ghizeh. The genius for dealing with large masses in building did not pass away with the pyramid-builders in Egypt, but their descendants continued to gain in