The superintendent has absolute authority over the two officials who are chiefly interested in the conduct of the trains over the division--the train-master and the train-despatcher. The first of these two officers, who must dove-tail their work both night and day, has the assignment of the train crews. His opinion will be called for whenever the vexed questions of seniority and promotion arise, and he will be asked to help to plan all extra or special freight and passenger trains. To show how this is done brings us close to the question of schedules, and we may pause for a moment to consider how this important phase of the railroad's operating is builded together. That time-table that you have just pulled from the folder rack seems at first glance an interminable mass of meaningless figures; yet when you come to find your journey upon it, it quickly simplifies itself, and you begin to marvel at the relation the figures bear to one another, how easily you may pick your course through the long columns of numerals. The more extensive time-tables that the railroad employees carry are quite as simple, and yet they are great feats of typographical composition. In reality, both these forms of printed time-tables are but transcripts of the real time-table of the division, which is kept set out upon a great board. This board is ruled in two directions. The regularly spaced intervals in one direction are marked as time, and represent time--one entire day of twenty-four hours. In the other direction of the board the stations are spaced in proportion to their actual spacing upon the line. The reproduction of a portion of such a board for an imaginary division of a railroad will illustrate. This line runs from Somerset to Rockville, 120 miles; and portions of it are double-tracked, the rest single-track, as shown at the top of the diagram. On the double-track, trains going in the same direction may pass one another only at the vertical lines, which represent station passing sidings, and on the single-track sections this rule holds, with the additional one, of course, that trains running in opposite directions may also pass one another at the vertical station lines. For economy of room only the seven hours from six o'clock in the morning until one o'clock in the afternoon are shown here. Following an old-time practice, odd numbers will represent up-bound trains, from Somerset to Rockville; even numbers, the down trains.