Figun ; Hoosac h\\n Workinc oi later stages with Burleigh pneumatic drills mounted on car- 

 riages. The bottom heading is being drilled in preparation for blasting out with nitroglycerine. Mill 

 i ■}■>" scale. (Smithsonian photo $260 M 



in which the engineering of tunnels is comprehen- 

 sively treated from the historical standpoint — some- 

 thing nol previously done in an American museum. 

 The guiding precept of the exhibit lias not been to 

 outline exhaustively the entire history of tunneling, 

 but rather to show the fundamental advances which 

 have 01 curred between primitive man's firsl systematic 

 use "I fire for excavating rock in mining, and the use 

 in combination ol compressed air, iron lining, and 

 movable shield in a subaqueous tunnel at the end of 



the l''lh century. This termination date was selected 



because it was during the period from about 1830 to 

 1900 that the most concentrated development took 

 place, and during which tunneling became a firmly 

 established and important branch of civil engineering 

 and indeed, of modern civilization. The techniques 

 ol present-da) tunneling are so fully related in cur- 

 rent writing that it was deemed far more useful to 

 devote the exhibit entirely to a segment of the field's 

 history which is less conmionlv treated. 



1 he major advances, which have ahead) been 

 spoken of as being ones of technique rather than 

 theory, devolve quite naturally into two basic classi- 

 fications: the one of supporting a mass of loose, 

 unstable, pressure-exerting material soft-ground tun- 

 neling; and the diametrically opposite problem of 

 separating rock from the basic mass when it is so 

 firm and solid that it can support its own overbearing 

 weight as an opening is forced through it rock, or 

 hard-ground tunneling. 



I" exhibit the sequence in a thorough manner. 

 inviting and capable of easy and correct interpreta- 

 tion by the nonprofessional viewer, models offered 

 the only logical means of presentation. Six tunnels 

 were selected, all driven in the 19th century. Each 

 represents either a fltndamem.il. new concept of 

 tunneling technique, or an important, early applica- 



tion hi one. Models of these works form the basis of 



the exhibit. No effort was made to restrict the work 

 in projei tson American soil. I his would, in i.n t. have 



been quite impossible 1 1 .ill . i . < urate pit hire Ol tunnel 



technology was to be drawn; for as in virtually all 

 other areas of technology, the overall development in 



this held has been international. I he art of mining 



was first developed highl) in the Middle Ages in the 

 tnic states; the tunnel shu-ld was invented by 

 .1 Frenchman residing in England, and the use of 

 compressed air to exclude the water from subaqueous 

 tunnels was firsl introduced on a major work by an 

 American. In addition, the two main subdivisions, 

 rock and soft-ground tunneling, are each intra 

 by a model not of an actual working, but of one 

 typifying early classical methods which were in use 

 fol ' ' nturies until the comparatively recent develop- 

 ment of mine efficient svvlems of earth Support uid 

 lock breaking. Particular attention is given to accu- 

 ol detail throughout the series of eight models; 

 original sources of descriptive and graphic information 

 were used in their construction wherever possible. In 

 all cases except the introductory model m the rock- 

 tunneling series, reprcsentins; copper mining bv earl) 

 civilizations, these sources were contemporary 

 accounts. 



The plan to use a uniform scale of reduction 

 throughout, in order to facilitate the viewers' inter- 

 pretation, unfortunately proved impractical, due to 

 the greal difference in the amount of area I 

 encompassed in different models, ami the necessity 

 that the cases holding them be of uniform height. The 

 related models of the Broadway and Tower Subways 

 represent short sections of tunnels only 8 feet or so in 

 diameter enabling a relatively large scale. 1'. inches 

 to the foot, to be used. Conversely, in order that the 

 model of Brunei's Thames Tunnel be most effective, 



PAPER 41: TUNNEL F.NCIMI RIM, A MUSEUM TREATMENT 



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