Page:Popular Science Monthly Volume 8.djvu/47

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ventive power of man was taxed to the utmost to provide machines for attack and defense. The ablest mathematicians and philosophers were pressed into the service, and helped to turn the scale in favor of their employers. The world has to regret the loss of more than one who, like Archimedes, fell slain by the soldiery while applying the best scientific knowledge of the day to devising means of defense during the siege. The necessity for roads and bridges for military purposes has led to their being made where the stimulus from other causes was wanting; and means of communication and the interchange of commodities, so essential to the prosperity of any community, have thus been provided. Such was the case under the Roman Empire. So, too, in later times, the ambition of Napoleon covered France and the countries subject to her with an admirable system of military roads. So, again, in this country, it was the rebellion of 1745, and the want felt of roads for military purposes, which first led to the construction of a system of roads in it unequaled since the time of the Roman occupation. And lastly, in India, in Germany, and in Russia, more than one example could be pointed out where industry will be benefited by railways which have originated in military precautions rather than in commercial requirements.

But to return to Rome. Roads followed the tracks of her legions into the most distant provinces of the empire. Three hundred and seventy-two great roads are enumerated, together more than 48,000 miles in length, according to the itinerary of Antoninus. The water-supply of Rome during the first century of our era would suffice for a population of 7,000,000, supplied at the rate at which the present population of London is supplied. This water was conveyed to Rome by nine aqueducts; and in later years the supply was increased by the construction of five more aqueducts. Three of the old aqueducts have sufficed to supply the wants of the city in modern times. These aqueducts of Rome are to be numbered among her grandest engineering works. Time will not admit of my saying any thing about her harbor works and bridges, her basilicas and baths, and numerous other works in Europe, in Asia, and in Africa.

In the fourth and succeeding centuries the barbarian hordes of Western Asia, people who felt no want of roads and bridges, swept over Europe to plunder and destroy. With the seventh century began the rise of the Mohammedan power, and a partial return to conditions apparently more favorable to the progress of industrial art, when widespread lands were again united under the sway of powerful rulers. Still, few useful works remain to mark the supremacy of the Mohammedan power at all comparable to those of the age which preceded its rise.

A great building-age began in Europe in the tenth century, and lasted through the thirteenth. While the building of cathedrals progressed on all sides in Europe, works of a utilitarian character, which