There was a sharp whistle, and Tom could see the lights of an engine passing out of a shed, to run a little distance down the line, then back on to another, and come smoothly along to where they stood--hissing, glowing, and bright. Tom saw at a glance that there was only an engine, tender, one carriage, and the guard's break; and, turning to the superintendent, "Can I ride on the engine with the driver?" he asked. "No. In with you." The superintendent opened the door of the saloon carriage, and shut him in. Then Tom heard him give a few quick, decisive orders to the guard, there was another sharp whistle, he waved his hand from the window, and the superintendent leaped on to the step: "Tell them to go as fast as possible," shouted Tom, as the train was gliding past the platform. "I have," the superintendent said quickly. "Hope she'll be better. Good night." As he spoke he leaped off at the end of the platform, and, shrieking and snorting, the little special went rather slowly along, past hissing goods engines and long black-looking trains, such as might be the funeral processions of an army. Lights flashed here and there, and far to right and left shone the glow of great London; while the big illuminated clock of the Parliament Houses loomed out of the darkness like a dull, fog-dimmed moon. "They are crawling!" Tom exclaimed, as he started up to look out from the window. But, as he did so, the wind was already beginning to whistle more quickly by his ears: they were clear of obstructions, and speed was getting up rapidly. There was the quick, throbbing beat, a crash as they passed under bridge after bridge, and soon after, as the engine gave a weird scream, they seemed to skim through a long station, whose row of pendant lights ran together like closely strung golden beads; and then, as Tom sank back in his seat, he felt the carriage begin to vibrate from side to side, and he knew that the telegraph had flashed its message, that the line was clear, and that, ever increasing in speed, they were off and away through the black darkness of the night--the best doctor in London speeding to the patient dying to hear his words. VOLUME TWO, CHAPTER FIFTEEN. A RIDE BY NIGHT. With the speed of the special train the excitement seemed to increase; but, for a time, Tom's attention was taken up by the stations they passed, and he tried hard to recall their names, referring at the same moment that they passed through to his watch, so as to endeavour to calculate the speed at which they ran.