Of all institutions of modern times, there is, perhaps, none so pre-eminently a people's institution as is the Post-office. Not only does it carry letters and newspapers everywhere, both within and without the kingdom, but it is the transmitter of messages by telegraph, a vast banker for the savings of the working classes, an insurer of lives, a carrier of parcels, and a distributor of various kinds of Government licences. Its services are claimed exclusively or mainly by no one class; the rich, the poor, the educated, and the illiterate, and indeed, the young as well as the old,--all have dealings with the Post-office. Yet it may seem strange that an institution which is familiar by its operations to all classes alike, should be so little known by its internal management and organisation. A few persons, no doubt, have been privileged to see the interior working of some important Post-office, but it is the bare truth to say that _the people_ know nothing of what goes on within the doors of that ubiquitous establishment. When it is remembered that the metropolitan offices of London, Edinburgh, and Dublin have to maintain touch with every petty office and every one of their servants scattered throughout England, Scotland, and Ireland; that discipline has to be exercised everywhere; that a system of accounting must necessarily be maintained, reaching to the remotest corners; and that the whole threads have to be gathered up and made answerable to the great head, which is London,--some vague idea may be formed of what must come within the view of whoever pretends to a knowledge of Post-office work. But intimately connected with that which was the original work of the Post-office, and is still the main work--the conveyance of letters--there is the subject of circulation, the simple yet complex scheme under which letters flow from each individual centre to every other part of the country. Circulation as a system is the outcome of planning, devising, and scheming by many heads during a long series of years--its object, of course, being to bring letters to their destinations in the shortest possible time. So intricate and delicate is the fabric, that by interference an unskilled hand could not fail to produce an effect upon the structure analogous to that which would certainly follow any rude treatment applied to a house built of cards. These various subjects, especially when they have become settled into the routine state, might be considered as affording a poor soil for the growth of anything of interest--that is, of curious interest--apart from that which duty calls upon a man to find in his proper work. Yet the Post-office is not without its veins of humour, though the metal to be extracted may perhaps be scanty as compared with the vast extent of the mine from which it has to be taken.