_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._