"You understand," he said, "that there are fifteen players on each side. But it would not do for the whole of these fifteen men to play in a crowd, for, in that case, if the other side forced the ball past them, they would have nothing to fall back upon--no reserves, as it were. Therefore, as we play the game in Scotland, ten men are told off to play in a knot. They are picked for their weight, strength, and endurance. They are called the forwards, and are supposed to be always on the ball, following it everywhere, never stopping or tiring. They are opposed, of course, by the forwards of the other side. Now, immediately behind the forwards are the two quarter-backs. They should be very active fellows, good dodgers and fast runners. They never join in the very rough work, but they always follow on the outskirts of the forwards, and if the ball is forced past it is their duty to pick it up and make away with it like lightning. If they are very fast they may succeed in carrying it a long way before they are caught--'tackled,' as we call it. It is their duty also to keep their eye on the quarter-backs of the enemy, and to tackle them if they get away. Behind them again are the two half-backs--or 'three-quarters,' as they call them in England. I am one of them. They are supposed to be fast runners too, and a good deal of the tackling comes to their lot, for a good runner of the other side can often get past the quarters, and then the halves have got to bring him down. Behind the half-backs is a single man--the back. He is the last resource when all others are past. He should be a sure and long kicker, so as to get the ball away from the goal by that means--but you are not listening." "Oh yes, I am," said Kate. As a matter of fact the great throng and the novel sights were distracting her so much that she found it hard to attend to her companion's disquisition. "You'll understand it quickly enough when you see it," the student remarked cheerily. "Here we are at the grounds." As he spoke the carriage rattled through a broad gateway into a large open grassy space, with a great pavilion at one side of it and a staked enclosure about two hundred yards long and a hundred broad, with a goal-post at each end. This space was marked out by gaily coloured flags, and on every side of it, pressing against the barrier the whole way round, was an enormous crowd, twenty and thirty deep, with others occupying every piece of rising ground or coign of vantage behind them. The most moderate computation would place the number of spectators at fifteen thousand. At one side there was a line of cabs in the background, and thither the carriage of the Dimsdales drove, while Tom rushed off with his bag to the pavilion to change.