In order to make clear what is involved in the handling of a great volume of mail such as is disposed of daily in this division of the New York office, it may be well to describe the course that is followed by a single letter. Assume that a letter is mailed in a street letterbox, in the district of a great terminal; it is brought in by a collector, who deposits it upon a long table surrounded by many employees. The table is likely to be what is known as a "pick-up table," which is one equipped with conveyor belts and convenient slide apertures for letters of different lengths, and into these apertures, with nimble fingers, the clerks grouped around it separate the mass of letters received, placing the letters with all the stamps in one direction. As quickly as they do so, the conveyor belts carry the letters, according to the different sizes into which they have been separated, to the electrically-driven canceling machines. These canceling machines are operated by a second group of employees, who feed in the letters, which are canceled at the rate of approximately 25,000 letters per hour. The whirling dies by which are imprinted the postmarks which cancel the stamps revolve at almost lightning speed. These postmarks are changed each half-hour, and the aim is to postmark the letters as rapidly as they come to hand, so that but a few minutes intervene between the time of mailing and time of postmark. This postmark is, in fact, the pace-maker. Once it is imprinted upon a letter, it can be determined by the postmark at any time just how long a time has been required for it to reach a particular point in the progress toward despatch. From the postmarking machine the letters are carried, sometimes by conveyors, sometimes by hand, and sometimes by small trucks, to what are known as the "primary separating cases." These cases are manned by employees who separate the letters into groups, according to certain divisions which facilitate the secondary and further distributions. Thus at the primary cases the letters are likely to be broken up into lots for the city delivery, for many different States, for foreign countries, and for certain large cities. Each separation on the primary case will likely be followed by a secondary separation almost immediately. A sufficient number of men is kept on the facing or pick-up tables, on the primary cases, and on the secondary cases and pouching racks, to maintain a continuous movement of the mails. The aim is to keep the mail moving not only continuously from the point of posting to the point of delivery, as nearly in a direct line as practicable, but rapidly also, and with only an arresting of the movement when this is made necessary by awaiting the departure of the next train.