"Good-night, old man. By the way, in case I forget it when you go, always carry a revolver with you up there, but never use it except as a last resort. That’s a good working rule for a European in an up-river district. Good-night." Another person besides Ted Burroughs was uneasy at the prospective transference of Errington to Sui-Fu. Mr. Ting, who knew everything that was going on, or at least as much as he wished to know, heard of it as soon as it was decided, and would have taken some trouble to prevent it if he could have urged anything definite against the character of Reinhardt. But he was a very discreet person. He had reasons of his own for maintaining cordial relations with Errington, and reflected that even at a distance he could still find means of looking after him. And when he learnt that Burroughs was to accompany his chum he felt more at ease; he had great confidence in the steady, down-right Mole. Reinhardt invited the boys to go up river in his motor-launch, a very powerful vessel in which he made his journeys between Shanghai and Sui-Fu. The launch had been bought out of the German navy as a condemned vessel; but some people remarked that if the Germans could afford to condemn vessels of this kind, their navy must be even more "tip-top" than was supposed. As the boys intended to take their hydroplane to their new quarters, they declined Reinhardt’s invitation, resolving to follow in the wake of the launch and test the relative speed of the two vessels. The hydroplane was now by no means identical in appearance with the vessel that had roused a passing curiosity at Plymouth. During the year they had been in China the boys had devoted all their spare time to turning it into a hydro-aeroplane. They replaced the original hull with a much lighter frame of canvas, fitting a kite-shaped half-keel under its forward part. They kept their engine, but adapted it to work two propellers, one at the stern, below the water-line, for driving the vessel through the water; the other raised some feet above the forepart, for driving it through the air. To the sides they fitted floats, and large planes, capable of being folded back when the vessel was to be used as a hydroplane, and adjustable at various angles. By means of differential gearing they contrived that the power of the water screw could be gradually reduced, while the air tractor gained in the same proportion. The effect of their arrangements was that as the speed in the water increased, the vessel rose a little; then, bringing into play an elevator and the tractor, they made the vessel rise completely out of the water and behave in all respects as an aeroplane.