Ralph explained the coasters and their use to his companion; and after they had put them on by means of an ingenious clutch, whereby the coaster could be snapped onto the shoe in less than five seconds, they both went out into the street. From each coaster a thin insulated wire led up the wearer's back to the hat or cap. Here it was attached to the _collector_, which was a stiff pin about eight inches long, projecting half-way out from the hat or cap. This pin sucked up, as it were, the high frequency electricity and carried it to the small motors, which latter propelled the coaster. To control the speed of the motor, one simply lifted up the front part of the coaster; this not only cut off the current, but automatically braked the two rear wheels. When the two rolled out in the street, Alice at once remarked upon the splendid condition of the roads. "You see," the scientist explained, "for centuries the city had to content itself with temporary pavements, until about fifty years ago it woke up and covered every street with steelonium. "You will notice that there are no cracks or fissures. Steelonium won't rust and is ten times as strong as steel. We now make our streets by putting down large slabs of the metal, six inches thick. After they are in place we weld them together electrically and the result is a perfect street composed of a uniform sheet of metal without cracks or breaks; no dirt or germs can collect. The sidewalks are made in the same manner. "As a matter of fact, the Tele-motor-coasters would not be possible were it not for the metallic streets. The flat spring which trails on the street between the two rear wheels must make continuous contact with the metallic 'ground,' else the current cannot flow." "But where does the current come from?" asked the girl. "You have perhaps noticed already the white slender posts at the edge of the sidewalk, and on their tops umbrella-like insulators which carry a thick spiked wire. This wire, as you see, is about fifteen feet above the curb and carries the high frequency current which not only supplies our coasters with power, by way of our needle collectors, but also propels all the vehicles which you see gliding so noiselessly." They were well under way and rolled along at a speed of about twenty miles an hour. They passed thousands of citizens, all coasting at high speed. There was no noise but the peculiar hum produced by the thousands of motors, a sound which was in nowise annoying.