Aging GracefullyEdison was sixty-four by this time and his role with his company and in life began to change. Edison left more of the daily operations of both the laboratory and the factories to others. The laboratory itself did less original experimental work and instead worked more on refining existing Edison products such as the phonograph. Although Edison continued to file for and receive patents for new inventions, the days of developing new products that changed lives and created industries were behind him.
In the 1915, Edison was asked to head the Naval Consulting Board. With the United States inching closer towards the involvement in World War One, the Naval Consulting Board was an attempt to organize the talents of the leading scientists and inventors in the United States for the benefit of the American armed forces. Edison favored preparedness, and accepted the appointment. The Board did not make a notable contribution to the final allied victory, but did serve as a precedent for future successful cooperation between scientists, inventors and the United States military. During the war, at age seventy, Edison spent several months on Long Island Sound in a borrowed navy vessel experimenting on techniques for detecting submarines.
Honoring a Lifetime of AchievementEdison's role in life began to change from inventor and industrialist to cultural icon, a symbol of American ingenuity, and a real life Horatio Alger story. In 1928, in recognition of a lifetime of achievement, the United States Congress voted Edison a special Medal of Honor. In 1929 the nation celebrated the golden jubilee of the incandescent light. The celebration culminated at a banquet honoring Edison given by Henry Ford at Greenfield Village, Ford's new American history museum, which included a complete restoration of the Menlo Park Laboratory. Attendees included President Herbert Hoover and many of the leading American scientists and inventors.
The last experimental work of Edison's life was done at the request of Edison's good friends Henry Ford, and Harvey Firestone in the late 1920s. They asked Edison to find an alternative source of rubber for use in automobile tires. The natural rubber used for tires up to that time came from the rubber tree, which does not grow in the United States. Crude rubber had to be imported and was becoming increasingly expensive. With his customary energy and thoroughness, Edison tested thousands of different plants to find a suitable substitute, eventually finding a type of Goldenrod weed that could produce enough rubber to be feasible. Edison was still working on this at the time of his death.