CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY. PAPER 41 TUNNEL ENGINEERING--A MUSEUM TREATMENT _Robert M. Vogel_ INTRODUCTION 203 ROCK TUNNELING 206 SOFT-GROUND TUNNELING 215 BIBLIOGRAPHY 239 FOOTNOTES INDEX [Illustration: Figure 1.--MINING BY EARLY EUROPEAN CIVILIZATIONS, using fire setting and hand chiseling to break out ore and rock. MHT model--3/4" scale. (Smithsonian photo 49260-H.)] _Robert M. Vogel_ TUNNEL ENGINEERING--A MUSEUM TREATMENT _During the years from 1830 to 1900, extensive developments took place in the field of tunneling, which today is an important, firmly established branch of civil engineering. This paper offers a picture of its growth from the historical standpoint, based on a series of models constructed for the Hall of Civil Engineering in the new Museum of History and Technology. The eight models described highlight the fundamental advances which have occurred between primitive man's first systematic use of fire for excavating rock in mining, and the use in combination of compressed air, an iron lining, and a movable shield in a subaqueous tunnel at the end of the 19th century._ THE AUTHOR: _Robert M. Vogel is curator of heavy machinery and civil engineering, in the Smithsonian Institution's Museum of History and Technology._ Introduction With few exceptions, civil engineering is a field in which the ultimate goal is the assemblage of materials into a useful structural form according to a scientifically derived plan which is based on various natural and man-imposed conditions. This is true whether the result be, for example, a dam, a building, a bridge, or even the fixed plant of a railroad. However, one principal branch of the field is based upon an entirely different concept. In the engineering of tunnels the utility of the "structure" is derived not from the bringing together of elements but from the separation of one portion of naturally existing material from another to permit passage through a former barrier. In tunneling hard, firm rock, this is practically the entire compass of the work: breaking away the rock from the mother mass, and, coincidently, removing it from the workings. The opposite extreme in conditions is met in the soft-ground tunnel, driven through material incapable of supporting itself above the tunnel opening. Here, the excavation of the tunneled substance is of relatively small concern, eclipsed by the problem of preventing the surrounding material from collapsing into the bore.