Dave's tactics were now purely defensive and evasive. There were five people aboard the aero-hydroplane, and they were desperate persons. He was not surprised when an object same shooting downwards from the Drifter. It struck one of the plane wires and then dropped earthwards. "Something's whipped loose," spoke Hiram quickly. "It's one of the elevator wires," said Dave, darting a quick glance at the spot. "This won't do." Now it was an over-water flight with no measured course to pursue. The Drifter tried to repeat its recent tactics. Dave noticed that the Monarch II had become somewhat faulty in its running. He was anxious to get away from the enemy. His main efforts were directed towards preserving a sure balance, for once or twice there was a wobble, as if the machine was hurt in some vital part. The young aviator made out a buoy a few miles to the west. Beyond it was a little settlement. He set his course for reaching it, and directed his full attention to the levers and the angle indicated. The indicator was directly in front of the pilot seat. It showed positively how the machine was flying, on the top or down bank. It comprised a cup with lines set about ten degrees, and gave a sure safety limit. Only the pendulum was movable. This was mounted on an arm always perpendicular, a small mirror reflecting the variations of the pendulum. Climbing and banking, Dave got quite a lead on the Drifter, but the aero-hydroplane kept up a steady pursuit. "There's something the matter besides the broken wire," spoke Dave to his anxious companion. "The oil intake is dogged or one of the planes loose. We can't take any risks." Dave sent the Monarch II on a downward shoot. There was a single pontoon in the center of the craft, with small tanks beneath the planes to prevent tipping over in the water. Dave aimed to hit the bay near to the shore. Suddenly the aircraft acted queer. It had evidently struck a hole in the air. The machine seemed fairly to drop from under its occupants, and thirty feet from the water, Dave was lifted from his seat and took a sudden plunge over-board. He went under the surface and came up dazed and nearly stunned. As he floated, dashing the water from his eyes, he saw the Drifter, now a flying boat, cut around a point of rocks, bearing straight down upon him. Dave looked quickly about him for the Monarch II. To his surprise, as it scudded across the waves for perhaps a hundred feet on its momentum, it lifted again free of the surface of the bay. He made out Hiram clambering from his seat like a sailor among the riggings of a ship. He saw the machine go up on a sharp slant, clear the shore of the bay, and disappear beyond the high cliffs lining it. Then something struck him. It was some light part of the rotary engined aero-hydroplane, the Drifter, cutting the water like a knife. His head dizzied, and the young aviator went under the surface of the lake with a shock. CHAPTER XXII