Then there is another item which adds to the complexity, which is this--that the greater the weight, the longer the time required for pulling up. It would seem, therefore, as if a heavy weight, to a certain extent, assisted its own propulsion. The same circumstances are observed on the railways, and, probably, from the hardness of the metal on which their wheels run, it is still more apparent than on a road. I was once travelling for a short distance upon a locomotive engine without a train behind it, and upon asking the driver how long it would take to bring his engine to a standstill, he said, "I could stop it almost immediately now, but it would be very different with a long train behind her." Probably there are few coachmen who have driven any great number, of miles through whose brain this question has never trotted, but without arriving at any solution of it. At any rate, I confess my own ignorance, and only throw down the question at the feet of science after the custom of the ages of chivalry, when the herald threw down the gauntlet into the midst of the assembled knights, to be picked up by the best man. The following narrative will convey some idea of the force of velocity which appertains to the wheels of a coach travelling at a high speed:-- As the "Mazeppa" coach was proceeding on her journey from Monmouth to Gloucester, when descending a hill about three miles from the former place at a fast pace, the tire of the near hind wheel came off, and the impetus was so great that it caused it to pass the coach and run on for nearly half a mile, thus proving that the power required to draw a carriage when it has attained much speed must be very much diminished. It only requires to be kept moving. CHAPTER IX. A NOTE ON THE HORN. Many guards on the day coaches carried key bugles, on which some of them were able to play exceedingly well, and helped to while away many a half hour on the journey; but on the mails and night coaches, the former especially, straight horns were employed. Formerly these were all made of tin, hence the "yard of tin," but in later years a good many copper or brass ones came into use, and a few, in quite late years, adopted a twisted horn without keys, much like the infantry field bugle used in the army. [Illustration: J. Sturgess del. et lith. M&N. Hanhart imp. OBSTRUCTION ON THE BRIDGE.]