In 1915, Atwood Aeronautic Co, Williamsport,PA presents its water-cooled, 12-cylinder, H engine delivering 120 hp at 2,000 rpm and 150 hp at 2,500 rpm. If gear is used, the engine is spinning at 3,200 rpm with 190 hp. It is the model 12-180.

"Atwood M-1"

"Atwood, side viewl"

-In 1916 They present the water-cooled M-1, with 12 cylinders in V giving 140 hp, and the M-2 with 350 hp. We do not have any information about the Twin Six from 1915.