During the 1909 Alaska–Yukon–Pacific Exposition, held in Seattle (held on the site of the present-day University of Washington), the young Hamilton, now at the age of 14, had a job of repairing hot-air balloons. This job would also allow him to ride what he repaired (possibly a type of insurance policy to ensure the balloons were fixed properly) which helped fuel his continuing interest in aviation. Also, during this time, Hamilton and a school friend, Paul J. Palmer established a partnership and called their company “Hamilton and Palmer”. Their office and factory were located in their respective parents' garage and kitchen tables. The two built and experimented with various biplane glider designs of the time. The two quickly gained a better understanding of the principles of how aircraft worked and were put together. Three gliders were actually built and flown around the steep hills around their neighborhood in Seattle called Leschi which was on the west shores of Lake Washington. There was only one mishap. The second glider jerked out of the hands of Palmer and soared away and crashing into pieces blocks away. Many years later, Hamilton would recall that even though he got a scar on his left hand from one of the flights, he had learned how to fly from those tests.