Boulevard Engine Co in Saint Louis, Missouri, built a 30/35 hp, four-cylinder, water-cooled engine in 1910.

-In 1911 they also made a water-cooled, eight-cylinder V-engine that delivered 60/70 hp.

-The Boulevard aircraft engine from 1910 had four upright cylinders in line and was water cooled.

-The engine had an iron block, aluminum crankcase, and an overhead cam shaft that controlled the valves directly.

"The Boulevard from 1910, without sump"

-The engine from 1910 gave 20-25 hp at 1,700 (?) rpm.

-The 1911 model that delivered 30-35 hp, is shown in a photo that is taken from the intake side.

"Boulevard from 1911"

-We can clearly see that ignition is already by magneto and the mixture is produced by carburetor.

From appendix 10: We have found an ad from 1910 with the upright, 4-cylinder, 35 hp engine built by Boulevard Engine Co of St. Louis.

"Boulevard ad with 4L and V8 engines"