Two posts, painted white and in line with each other--one almost at the river's edge, the other 150 feet back--marked the starting-line of a measured mile, and were eagerly watched by the men aboard the yacht. She sped toward the starting-line as a sprinter dashes for the tape; almost instantly the two posts were in line, the men with watches cried "Time!" and the race was on. Then began such a struggle with Father Time as was never before seen; the wind roared in the ears of the passengers and snatched their words away almost before their lips had formed them; the water, a foam-flecked streak, dashed away from the gleaming white sides as if in terror. As the wonderful craft sped on she seemed to settle down to her work as a good horse finds himself and gets into his stride. Faster and faster she went, while the speed of her going swept off the black flume of smoke from her stack and trailed it behind, a dense, low-lying shadow. "Look!" shouted one of the men into another's ear, and raised his arm to point. "We're beating the train!" [Illustration: THE STEAM TURBINE-DRIVEN _VELOX_, OF THE BRITISH NAVY The fastest torpedo-boat destroyer.] Sure enough, a passenger train running along the river's edge, the wheels spinning round, the locomotive throwing out clouds of smoke, was dropping behind. The train was being beaten by the boat. Quivering, throbbing with the tremendous effort, she dashed on, the water climbing her sides and lashing to spume at her stern. "Time!" shouted several together, as the second pair of posts came in line, marking the finish of the mile. The word was passed to the frantically struggling firemen and engineers below, while those on deck compared watches. "One minute and thirty-two seconds," said one. "Right," answered the others. Then, as the wonderful yacht _Arrow_ gradually slowed down, they tried to realise the speed and to accustom themselves to the fact that they had made the fastest mile on record on water. And so the _Arrow_, moving at the rate of forty-six miles an hour, followed the course of her ancestress, the _Clermont_, when she made her first long trip almost a hundred years before. The _Clermont_ was the first practical steamboat, and the _Arrow_ the fastest, and so both were record-breakers. While there are not many points of resemblance between the first and the fastest boat, one is clearly the outgrowth of the other, but so vastly improved is the modern craft that it is hard to even trace its ancestry. The little _Arrow_ is a screw-driven vessel, and her reciprocating engines--that is, engines operated by the pulling and pushing power of the steam-driven pistons in cylinders--developed the power of 4,000 horses, equal to 32,000 men, when making her record-breaking run. All this enormous power was used to produce speed, there being practically no room left in the little 130-foot hull for anything but engines and boilers.