The Hall-Scott A-1 was an early aircraft engine.

The Hall-Scott Motor Car Company began specializing in the construction of airplane engines in 1911.

At the Third International Aviation Meet in Los Angeles in 1912, a Hall-Scott A-1 powered an aircraft designed by Jay Gage of Los Angeles and flown by Charles Stevens.

During the 1912 International Aviation Meet in Oakland, Hillery Beachey, brother of famed aviator Lincoln J. Beachey, flew a biplane powered by an A-1.

Data from Airplane Engine Encyclopedia[1]