In 1910-1912 BROC presents an upright 4-cylinder engine that gave 50 CV (see Helium).

From appendix 6: The engine uses the two-stroke cycle and has automatic intake valves in the cylinder head and there is are exhaust vents located at the BDC.

"Broc engine view"

-We can see that in the group of the two front cylinders there are same uncovered sections to distinguish the pistons inside.