The Tunnels of the Ancients.
LEAVING Naples by carriage, the road immediately leads through a tunnel three-quarters of a mile long, and cut right through a mountain 800 feet high. This tunnel is driven through a volcanic tufa. This tunnel of Posilippo, as it now exists, was cut through only twenty-seven years before Christ. Augustus Cæsar's great minister of public works, Marcus Agrippa, made the present tunnel, or he may have enlarged it from a smaller one that answered the commercial communications and necessities of the days before the empire. This tunnel is to-day the great highway to the heart of Naples, as it has been for more than 1900 years. The great Appian way ran to Capua, within thirty miles of Puteoli; thence this magnificent Roman high-road, under the name of the Consular Way, was continued to Puteoli, and the then Consular Way pushed on through Neopolis, Herculaneum, Pompeii, Stabia, Nucera, Salernum, Paestum, down to Rheulm. This tunnel of Posilippo was formerly called the grotto or tunnel of Puteoli. The ancients began their perforations at each end, and also from above, in two places equidistant from the termini of the tunnel. The guide-books, both Murray and Baedeker, tell that shafts from above were made by Alfonso I., in the fifteenth century, which is altogether wrong. No less than four tunnels of Roman construction exist in the vicinity of Naples, and they, all of them, even the latest, rediscovered and opened in 1842, have shafts from above. The Romans were great road, tunnel, and bridge builders, and we have never given their engineers half the credit which we should for their great science and skill. Nowhere, not even in the city of Rome or on the Roman Campagna, are there so many evidences of their engineering skill as are to be found in the vicinity of Naples. At a recent meeting of the British Association of Science, held at Aberdeen, Scotland, Mr. B. Baker, an eminent British civil engineer, read a paper recalling certain engineering feats of the ancients. Mr. Baker says: "I have no doubt that as able and enterprising engineers existed prior to the age of steam and steel as exist now, and their work was as beneficial to mankind, though different in direction. In the important matter of water supply to towns, indeed, I doubt whether having reference to facility of execution, even greater works were not done 2000 years ago than now. "Herodotus speaks of a tunnel eight feet square and nearly a mile long, driven through a mountain in order to supply the city of Samos with water; and his statement, though long doubted, was verified in 1882, through the abbot477of a neighboring cloister accidentally unearthing some stone slabs. The German Archæological Society sent out Ernest Fabricius to make a complete survey of the work, and the record reads like that of a modern engineering undertaking. Thus, from a covered reservoir in the hills, proceeded an arched conduit about 1,000 yards long, partly driven as a tunnel and partly executed on the 'cut and cover' system, adopted on the London underground railway. The tunnel proper, more than 1,100 yards in length, was hewn by hammer and chisel through the solid limestone rock. It was driven from the two ends like the great Alpine tunnels, without intermediate shafts, and the engineers of 2400 years ago might well be congratulated for getting only some dozen feet out of level, and little more out of line. From the lower end of the tunnel, branches were constructed to supply the city mains and fountains, and the explorers found ventilating shafts and side entrances, earthenware socket-pipes with cement joints, and other interesting details connected with the water supply of towns." This tunnel of Posilippo is also a fine specimen of ancient engineering. Millions of human beings have each year, for nearly twenty centuries, passed through it. Roman chariots and other ancient vehicles have left their autographs scraped and scratched into the lining stone, and modern wagons and carriages still rub their hubs against it. Strabo wrote about this tunnel. Seneca described his passage through it. Petronius satirized it, and Petrarch, Boccaccio, Cappaccio, and more modern writers have told us their thoughts about it; and it seems good for a thousand years to come. Virgil's tomb is just above its eastern entrance, and his farms (where he wrote part of both the "Georgics" and the "Æneid") are over it.—Scientific American.