Hoosac TunnelArticle Free Pass Hoosac Tunnel, the first major
rock tunnel built in the United States. The tunnel runs through
Hoosac Mountain of the Berkshire Hills, east of North Adams,
Mass., and was built to provide a rail connection between Boston
and upper New York state. Though only 4.75 miles (7.6 km) long,
the tunnel took 24 years (1851–75) to complete, partly because
of slow and laborious rock-tunneling techniques in use when
construction began, and partly owing to financial and political
difficulties. Nevertheless, the tunnel, begun under the
direction of Herman Haupt and completed by the firm of W. & J.
Shanley of Montreal, provided a notable first in civil
engineering—the use of nitroglycerin as a blasting agent. This
practice was introduced, along with electric firing, by Thomas
Doane, the resident engineer. Even more important, the
development of compressed-air drilling machinery on the Hoosac
helped launch the American pneumatic-tool industry, which
assumed immense significance in mining and co