Between the two blocks is a loading and unloading yard for the mails, and on the west side of the second block is a large yard and unoccupied space left for such future additions as may be required for growth of work. The Post Office is learning from experience the value of the margin, and that there is no finality in its advances. It is in this open space below the level of the ground where is to be found the section of the Roman wall which I have described. The public office is the central office in London for the transaction by the public of all classes of postal and telegraphic business. It is the largest public post office in the country, and measures 152 feet by 52 feet, with a counter running the whole length. The inside walls are lined throughout with marble; a green Irish marble being used for the dado, pilasters, panels, door architraves, and the front of the counter, and a light Italian marble for the remainder. The pilasters and piers have bases and capitals of bronze, and bronze is also used for the counter edges, table edges, and electric light fittings. All this is unaccustomed magnificence for a London post office, and he must be a man singularly deficient in a sense of the fitness of things who can enter these marble halls and boldly go up to the bronze-edged counter and ask for a halfpenny stamp. Under the public office is the posting room, into which falls the correspondence posted in the big letter-boxes by the public. It is interesting to stand in this room and watch the postal packets pouring down the shoot from the letter-boxes. There begins the first stage of the travels of a letter. Everything that machinery and science can do to economise labour and to facilitate delivery and despatch is brought into play. Sorting is simply continual subdivision, and it is interesting to watch the journeyings of the letters from the moment of posting in the big letter-box. There is very little carriage from one place to another by hand. Cable conveyors and band conveyors, worked much on the same principle as the moving platforms we have all seen at exhibitions and great emporiums, carry the letters from point to point until each letter finds its appointed bag, and is either taken out of the building by the City postman or deposited in a mail cart which takes it to the railway station or district office. A band conveyor takes the letters from the posting room which are addressed to places in London or abroad, to the ground floor of the building in baskets, and the empty baskets are sent down by a return band. The correspondence for the provinces, which is dealt with at a large sorting office at Mount Pleasant, nearly a mile away, is put into bags, and another band conveyor takes these bags to the departure platform at the west end of the sorting office. There is a third band conveyor suspended from the ceiling of the same floor, which is for the conveyance of bags of mails from the east to the west of the sorting office.