I suppose most of my readers have seen a big balloon--if not, a word of explanation may be necessary here. The body of the balloon is, of course, a great sack or bag of some excessively fine and light material, such as silk, or layers of india-rubber, between sheets of linen covered with thick coats of varnish. Over the balloon is a kind of net-work of rope. This is its harness and comes to a point towards the bottom, where all the ropes are attached to a great wooden hoop, from which again hang the ropes to which the car itself is attached. Frank's idea was to climb up into the ring and cut the car adrift. 'You've hit the nail on the head, my lad, plum centre this time,' said Wharton, 'but can you get up to the ring yourself?' 'I'll try,' replied Frank, 'but there isn't a moment to lose. Give me a hand, Towzer.' Between them the others got Frank up into the rigging of the balloon, and tied him securely to the ring, so that he would not be entirely dependent upon his one arm for support. 'Are you all right?' cried Snap from his perch. 'All right, old chap.' 'All right,' came the answers. 'Then cut the ropes near you all together, so as not to drag the balloon, over on one side,' he cried. 'Now!' Each boy sawed away at the ropes near him with a will, but old Dick did not get his rope cut through quite as soon as the others. The result was that the balloon gave a furious plunge, and then, as the last rope broke, righted herself and darted upwards once more. Snap looked white and scared, but the colour came back to his face when he saw all his comrades in their places, and old Wharton chimed in with: 'Dang me if this here balloon hasn't got all the vices of a cayuse, and more. Loses its wind and wants to stop, leastways come down, and then, as for bucking, a half-broke cayuse is a fool to it!' For a while the balloon sailed along on a higher level, but all the time the thin wreath of white vapour marked a leak and a constant escape of gas. Besides this, the evening damp collected and settled on the envelope of the balloon, and all tended to weigh it down. 'We are sinking again,' cried Towzer, 'sinking faster than ever before. Look how the prairie is rushing up to meet us!' and indeed it seemed so, and there was absolutely nothing left to throw out. 'Wal, you may as well go too,' said Dick with a sigh, and he drew his revolver from his breast and dropped this his most precious possession to the earth. The boys looked at it as it shot downwards swift and straight, swifter and straighter than a skylark falls, and they thought of what might any moment be their own lot, and it made the boldest of them grip the ropes with fresh energy.