henson used the tubular boiler and the forced draught,[13]
thereby making steam rapidly enough for a short, quick stroke. In 1865 a
good freight locomotive weighing thirty tons could haul about forty
box-cars, each loaded with ten tons. This was the maximum load for a
level track; the average load for a single locomotive was about
twenty-five or thirty cars. Heavier locomotives could not well be used
because the iron rails went to pieces under them.

The invention of Bessemer steel produced a rail that was safe under the
pounding of a locomotive three or four times as heavy as those formerly
employed; it produced boilers that would carry steam at 250 instead of
60 pounds pressure per square inch. As a result, with only a moderate
increase in the fuel burned, a single locomotive on a level track will
haul eighty or ninety box-cars, each carrying nearly seventy thousand
pounds.[14]

The application of the double and the triple expansion principle has
been quite as successful with locomotive as with marine engines in
saving fuel and gaining power--that is, it has decreased the cost per
ton-mile of hauling freight and likewise the cost of transporting
passengers. Enlarged "fire-boxes," or furnaces,[15] enable steam to be
made more rapidly and to give higher speed.[16] Only a few years ago
forty-eight hours was the scheduled time between New York and Chicago;
now there are about forty trains a day between these two cities, several
of which make the trip in twenty-four hours or less.

=Railway Development.=--The railway as a common carrier, having its right
by virtue of a government charter, dates from 1801, when a tramway was
built between Croydon and Wandsworth, two suburbs of London. The rails
were iron straps, nailed to wooden stringers. The charter was carefully
drawn in order to prevent the road from competing with omnibus lines and
public cabs.

When the steam locomotive succeeded horse-power, however, there
followed an era of railway development that in a few years
revolutionized the carrying trade in the thickly settled parts of the
United States and Europe. Short, independent lines were constructed
without any reference whatever to the natural movement of traffic. There
seemed but one idea, namely, to connect two cities or towns. Indeed, the
absence of a definite plan was much similar to that of the interurban
electric roads a century later; local traffic was the only
consideration.

At first an opinion prevai