ppears to
have applied the high pressure principle before Trevithick, and it has
been said that Trevithick borrowed it from Evans, but Evans himself
never said so, and it is more likely that each of these inventors worked
it out independently. Watt introduced his steam to the cylinder at only
slightly more than atmospheric pressure and clung tenaciously to the
low-pressure theory all his life. Boulton and Watt, indeed, aroused
by Trevithick's experiments in high-pressure engines, sought to have
Parliament pass an act forbidding high pressure on the ground that the
lives of the public were endangered. Watt lived long enough, however, to
see the high-pressure steam engine come into general favor, not only in
America but even in his own conservative country.

Less sudden, less dramatic, than that of the cotton gin, was the
entrance of the steam engine on the American industrial stage, but not
less momentous. The actions and reactions of steam in America provide
the theme for an Iliad which some American Homer may one day write. They
include the epic of the coal in the Pennsylvania hills, the epic of
the ore, the epic of the railroad, the epic of the great city; and, in
general, the subjugation of a continental wilderness to the service of a
vast civilization.

The vital need of better transportation was uppermost in the thoughts of
many Americans. It was seen that there could be no national unity in a
country so far flung without means of easy intercourse between one group
of Americans and another. The highroads of the new country were, for the
most part, difficult even for the man on horseback, and worse for those
who must travel by coach or post-chaise. Inland from the coast and
away from the great rivers there were no roads of any sort; nothing but
trails. Highways were essential, not only for the permanent unity of the
United States, but to make available the wonderful riches of the inland
country, across the Appalachian barrier and around the Great Lakes, into
which American pioneers had already made their way.

Those immemorial pathways, the great rivers, were the main avenues of
traffic with the interior. So, of course, when men thought of improving
transportation, they had in mind chiefly transportation by water; and
that is why the earliest efforts of American inventors were applied to
the means of improving traffic and travel by water and not by land.

The first men to spend their time in trying to apply steam