There was a smile of deep satisfaction on John's own bronzed features as he put the question, a smile which was duplicated on the faces of his three co-workers--Paul, Bob, and Tom Meeks.  It was the latter part of March, Easter vacation week for Paul and Bob, and the two chums had been working every one of the last three days helping John and Tom put the finishing touches on the big new airplane.  And now this Friday morning it rested gracefully upon its own rubber-tired wheels, its great stretch of wings spread out as airily as those of a monster bird, its huge two-bladed propeller glistening like burnished silver, and its body running backward in a splendid symmetrical taper, to end at the well-proportioned tail.  Sky-Bird II was done at last.