Engineering Wonders of the World
Volume I

ANCIENT ENGINEERING. 19 A ROMAN ARCH BRIDGE ACROSS THE DANUBE. {From Arch of Trajan.) were solidly and scientifically built, arches of 120 feet span being not unknown. A branch of engineering in which the ancients showed considerable skill was that of tunnel- ling. King Hezekiah, who reigned in Jerusalem about 700 b.c., “ fortified his Great Roman Tunnels. maintain a correct level, but were somewhat astray in the horizontal alignment. Coming a little nearer the present day, we find the Greek Eupalus driving, in 625 b.c., a tunnel 8 feet square and nearly a mile long to bring water into Athens. The so- called Grotto of Posilippo, near Naples, is an old Roman road tunnel 2,316 feet long, 22 feet wide, and 89 feet high on the average—surely a notable tunnel- ling feat! Yet it was a mere bagatelle to the making of a drainage tunnel, at the order of the Emperor Claudius, to empty Lake Fucinus into the Liris. This tunnel was 3 miles long, and for thousands of feet penetrated hard carnelian that had to be chipped away painfully with the chisel. Reviewing the work done, we may wonder what tools the workers used. It remains a mystery how the Egyptians hewed, squared, and carved their granite pillars and colossi. A Jewish city by lead- Tunnel. ing water into it, and he bored through the rocks with bronze and dammed the water into a pool.” * The boring referred to is probably the. Shiloah Tun- nel, some 580 yards long, in which has been discovered an inscription setting forth that the boring was con- ducted from both ends sim- ultaneously — a statement curiously confirmed by the fact that the tool marks on the walls in the two halves run in opposite directions. The breadth of the tunnel varies from 2 to 3 feet, its height from 6 to 10 feet. The engineers managed to * Sirach. An intefesting instance of ideas perpetuating themselves. The instruments shown are “ stakes,” or field anvils, used for straightening the edge of a scythe or sickle. Nos. 1 and 3 are such as aro manufactured to-day at Birmingham. Nos. 2. and 4 are of Roman make, dating from about 300 a.d. Observe the exact reproduction of the rings in the respective types. Photo, V. White and Co., Reading.