Slowly, surely the Sky-Bird overtook the rival machine.  When it seemed her nose was almost up to the tail of the _Clarion_, they saw a movement in the bottom of the fuselage of the craft above them, where her trapdoor of glass was situated in the floor of the cabin.  Then something gray streaked down through the air.  It went whizzing by just in front of the Sky-Bird, and a few moments later plunged into the sea with a great splash.