Then while John and Tom went industriously to work, Paul and Bob rode away to Clark Polytechnic in New York with Mr. Giddings.  Just before starting into the city that morning, the newspaper man had met Tom, and there was little doubt that he was well pleased with this addition to his force of workers.  Of course Paul and Bob were sorry to have to interrupt their labors on Sky-Bird II, but there was no help for it, and there was some consolation in the thought that undoubtedly their instructors would let them work on some of the airplane's smaller parts as a portion of their school mechanical practice.  This supposition indeed proved correct, and as the fall days passed they found the two student chums not only partaking with full spirit in the sports of their comrades, but also contributing in no small measure to the progress of the work on the new airplane.