That was low enough.  All this time the propeller had been spinning from the rush of air alone.  Now John threw in the clutch; the revolving propeller shaft grabbed the crankshaft of the engine, and once more it began its rhythmic purr.  Just a little upthrust of the tail-elevators and ailerons brought them again into the horizontal in a huge swoop.  Nothing could have been prettier.  They had escaped the terrible tornado, leaving it still galloping westward far behind them, and were once more in normal position for continuing their flight toward the goal!