The working of the mail bag exchange apparatus is perhaps to the public the most interesting feature in the Travelling Post Office. I make no apology, therefore, in giving a detailed description of the contrivance. The net is made of hemp, the end of which is strengthened by stout manilla rope in order to enable it better to withstand the shock subsequent upon the receipt of the pouches. The iron frame of the net is hinged in two pieces, called the bed and the wing. When extended for use the net is about two feet seven inches from the panel of the carriage, and the apex of the wing some nine feet eight inches above rail level. When not in use the net pulls up nearly flat against the side of the carriage, and it is lowered into position and raised again by the action of a lever inside the carriage. The delivery arms are fitted in the doorways of the carriage, and are hinged to strong iron tubes containing spiral springs which, when the arms are not required for use, retain them in an upright position by the door pillars. When a despatch has to be made the arm is drawn into the carriage, a sort of convex shield, technically called “a sweep,” determining the angle to which it must be brought before it can be drawn from its perpendicular position. The mail bags for delivery are enclosed in a leather pouch for protection against concussion, and to keep them in a fairly square position when suspended. Affixed to the pouch is a thick strap about ten inches long, known as a “drop strap,” and at one end of this there is an eyelet which, when the arm is drawn into the carriage, is passed on to a pin forming a portion of the head or box of the arm, which is protected by a spring cover. The carriage net has to be lowered and the pouches put out for delivery some distance before the roadside apparatus is reached, and in order to perform these operations properly an officer has to be well acquainted with the different landmarks along the permanent way. All sorts of immovable marks serve for this purpose—houses, churches, bridges, gates, and clumps of trees. There is a tale told of a white horse which was seen so regularly every day in a field beside the railway that the animal became a mark for the official working the apparatus. One day the horse died, and there were then several bag failures at the particular station. ------------------------------------------------------------------------ [Illustration] _Photos by_ _Herbert Lazenby._ THE TRAVELLING POST OFFICE. (1) The official placing the suspended pouch in position to be taken up by the passing train. (2) The pouch suspended and the net open to receive the pouch from the approaching train. (3) The pouch has been received into the travelling post office by means of the net attached to it, while the one received from the train is seen in the wayside net.