27 ene 1940 año - 1931 : Electric razor
1932 : Radio telescope; parking meter; folding wheelchair
1933 : Electron microscope; angle-poise lamp
1934 : Cats eyes
1935 : Electric guitar
1936 : Sun tan lotion; electric blanket
1938 :Ballpoint pen; photocopying
1939 : Helicopters; cloud seeding to trigger rain