operator can easily recognise his marks; but in a very dark night, or during a fog, his skill and experience are put to the test. On such occasions he seems to be guided by the promptings of his collective senses. He puts his face close to the window, shutting off the light from the carriage with his hands, and peers into the darkness, trying to recognise some wayside object; he listens to the noise made by the train, estimates its speed of travelling, and by these means he judges of his position, and effects the exchange of the mails. It is indeed marvellous that so few failures take place; but this is an instance of how, by constant application and experience, things are accomplished which might at first sight be considered wellnigh impossible. When the exchange takes place, it is the work of a moment--"thud, thud." The arm which bore the bag springs, disengaged, to the side of the carriage; the operator takes the inwards bag from the net, draws the net close up to the side of the vehicle, and the whole thing is done, and we are ready for the next exchange. The blow sustained by the pouch containing the mail-bag at the moment of delivery, on occasions when the train is running at a high speed, is exceedingly severe, and sometimes causes damage to the contents of the bags when of a fragile nature and these are not secured in strong covers. A bracelet sent by post was once damaged in this way, giving rise to the following humorous note:-- "Mr ---- is sorry to return the bracelet to be repaired. It came this morning with the box smashed, the bracelet bent, and one of the cairngorms forced out. Among the modern improvements of the Post-office appears to be the introduction of sledge-hammers to stamp with. It would be advisable for Mr ---- to remonstrate with the Postmaster-General," &c. [Illustration: Delivering Arm, showing how the Pouch is suspended.]