The miles of annual transportation of mail by railroad in 1852 amounted to 11,082,768, which increased to 113,995,318 in 1882, with an increase in the number of Railway Mail Service employees from 43 in 1846 to 3,072 in 1882. This wonderful expansion was but proportional with the development of the country at large. At the close of the war of the Rebellion, business was at its height. Industry and intelligence were seeking together new channels for their diffusion. The Pacific Railway was the grand conception that met this demand, and by its means were united the borders of the continent, and communication thus made more frequent and rapid between our interior, the West, and Europe: the most ancient civilization of the world in the Orient greeted the youngest in the Occident, and completed the girdle about the earth.

The lumbering stage and caravan laboring across the plains, and the swift mustang flying from post to post, frequently intercepted by the wily savage, were but things of yesterday, though fast becoming legendary. When those slower methods by which correspondence was conveyed at a great expense and delay, and current literature was to a great extent debarred, were supplanted by a continuous line of stages, it was considered a revolution in the wheel of progress, and the consummation. The possible accomplishments of the present day, if entertained at all at that time, were in general considered Munchausen, and not difficulties to be surmounted by practical engineering and undaunted perseverance. The civilization of the world has kept pace with its channels of communication and has accordingly rendered invaluable aid to it. In our country the field in this direction is exceedingly broad.

There is no branch of the government service that reaches so near and supplies the wants of the people as the Post-Office Department, and whose ramification may not be inaptly compared to the human system with its arteries filled with the life-current coursing through the veins and diffusing health and vigor to the various parts; in the same manner the people in the different sections of the country interchange their information. The centres of art and literature, conveying to the vast producing region in the West the products of their refined taste, scientific research, and mechanical achievements, keep alive and propagate the spirit of inquiry, making remote parts of the nation homogeneous in tastes, knowledge, and a common interest in all matters of national advancement.

If a map of the United States with every railway that crosses and recrosses its broad surface were laid before us, it would appear that a regulated system for an expeditious transmission of the mails in such an intricate confusion of lines, apparently going nowhere yet everywhere, would be an impossibility; but by study and untiring energy this has been accomplished.

The machinery of the Post-Office Department is a system of cog-fitting wheels, in all its component parts; and were it not so, in the necessarily limited period and space allotted, the work in postal-cars could not be successfully accomplished.

The interior dimensions of postal-cars vary, from whole cars sixty feet in length, to apartments five feet five inches in length by two feet six inches in width. The most comprehensive conception of the practical working of the postal-car system, can be formed in a railway post-office from forty to sixty feet in length; with this in view, we will make a trip in one.