INTRODUCTION 



THE HISTORICAL DEVELOPMENT OF TUNNEL 



BUILDING. 



A TUNNEL, defined as an engineering structure, is an artificial 

 gallery, passage, or roadway beneath the ground, under the bed 

 of a stream, or through a hill or mountain. The art of tunnel- 

 ing has been known to man since very ancient times. A The- 

 ban king on ascending the throne began at once to drive the 

 long, narrow passage or tunnel leading to the inner chamber or 

 sepulcher of the rock-cut tonib which was to form his final 

 resting-place. Some of these rock-cut galleries of the ancient 

 Egyptian kings were over 750 ft. long. Similar rock-cut tun- 

 neling work was performed by the Nubians and Indians in 

 building their temples, by the Aztecs in America, and in fact 

 by most of the ancient civilized peoples. 



The first built-up tunnels of which there are any existing 

 records were those constructed by the Assyrians. The vaulted 

 drain or passage under the southeast palace of Nimrud, built by 

 Shalmaneser II. (860-824 n.c.), is in all essentials a true soft- 

 ground tunnel, with a masonry lining. A much better exam- 

 ple, however, is the tunnel under tin; Euphrates River, which 

 may quite accurately be claimed as the first submarine tunnel 

 of whirh there exists any record. It was, however, built under 

 the dry bed of the river, the waters of which were temporarily 

 diverted, and then turned back into their normal channel after 

 the tunnel work was completed, thus making it a true sub- 

 marine tunnel only when finished. The Euphrates IJiver tun- 

 nel was built through soft ground, and was lined with brick 



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