It was late in the afternoon--just before dusk, when the winds would be at their quietest, and others not likely to be present--that our friends arrived at the field.  There was not a soul to be seen.  Paul, who had carried his precious Sky-Bird, freed it from the wrapper and held it up for Mr. Giddings to see.  The night before he and John had put the finishing touches to the delicate structure by adding another coat of varnish and attaching the little rubber-tired aluminum wheels to the axle.