, however, only made possible from the financial
standpoint by the Post Office monopoly of the carriage of letters,
although that monopoly is justified on other grounds. With a uniform
rate, owing to the varying conditions under which the service is
conducted in different districts, there is inevitably a variation in the
amount of profit. In certain cases, the rate is actually unprofitable;
and were private undertakings permitted to compete for the more
profitable traffic, such as the local traffic in large centres of
population, the profits of the Post Office would be reduced to
vanishing-point.

Improvements in the means of communication have naturally had
considerable effect on the development of the Post Office. The
introduction of the stage-coach in the eighteenth century, and of
railways and steamboats in the nineteenth, in turn revolutionized the
methods of general transportation. By these improvements the capacity of
the Post Office was largely increased, and regularity, rapidity, and
increased frequency of service made possible. But such general
improvements, while of the utmost importance as regards the capacity and
character of the Post Office service, can affect the rates of postage
only so far as they affect the cost of transportation of the mails, or,
by largely increasing traffic, enable economies of business on a large
scale to be secured. The stage-coach cheapened the cost of
transportation, but, in England, had no effect on the rates of postage,
because at the time of its introduction the charges were of a purely
fiscal character, and the benefit of cheaper transportation was not
passed on to the users of the Post Office. The effect of the
introduction of the railway has, at any rate as regards letter postage,
not been much greater. Sir Rowland Hill's reform, which standardized
letter postage, was based on the ascertained cost of conveyance of mails
by stage-coach.[634] He found the cost of such conveyance too small to
be taken into account; and the introduction of the railway could not, of
course, improve such a situation.[635]

The ordinary light letter, weighing on the average considerably less
than an ounce, comprises the overwhelming bulk of Post Office traffic,
and the heavier letters occupy a quite subsidiary place. With the growth
of Post Office traffic, and the consequent economies resulting from
business on a large scale, the profits of the Post Office have gradually
increased, but not to s