Almost simultaneously with the construction of the Tower Subway,
the first American shield tunnel was driven by Alfred Ely Beach
(1826-1896). Beach, as editor of the _Scientific American_ and
inventor of, among other things, a successful typewriter as early as
1856, was well known and respected in technical circles. He was not
a civil engineer, but had become concerned with New York's pressing
traffic problem (even then) and as a solution, developed plans for a
rapid-transit subway to extend the length of Broadway. He invented a
shield as an adjunct to this system, solely to permit driving of the
tunnel without disturbing the overlying streets.
An active patent attorney as well, Beach must certainly have known of
and studied the existing patents for tunneling shields, which were,
without exception, British. In certain aspects his shield resembled
the one patented by Barlow in 1864, but never built. However, work on
the Beach tunnel started in 1869, so close in time to that on the
Tower Subway, that it is unlikely that there was any influence from
that source. Beach had himself patented a shield, in June 1869, a
two-piece, sectional design that bore no resemblance to the one used.
His subway plan had been first introduced at the 1867 fair of the
American Institute in the form of a short plywood tube through which
a small, close-fitting car was blown by a fan. The car carried 12
passengers. Sensing opposition to the subway scheme from Tammany, in
1868 Beach obtained a charter to place a small tube beneath Broadway
for transporting mail and small packages pneumatically, a plan he
advocated independently of the passenger subway.
[Illustration: Figure 30.--CONTEMPORARY ILLUSTRATIONS of Tower
Subway works used as basis of the model in the Museum of History
and Technology. (_Illustrated London News_, 1869.)