The engine was a 4-cylinder "Moteur Rotatif" (I hope, this maybe the correct translation in English: "Radial Engine"),...
The radial engine, with its cylinders in a star-form feeding a single crank, can be either static or rotary and were common on aeroplanes. The static kind (which was the most used) had the crankcase and cylinders fixed to the airframe and the crankshaft turning to drive a propellor.
In the early days there was concern that the air-cooled cylinders would overheat, so the rotary was invented where the crankshaft is rigidly attached to the airframe and the crankcase and cylinders revolve around it and drive the propellor. Well-known examples were made by Gnome, Clerget, Oberursel and Le Rhone.
I think "Moteur Rotatif" is what we call the rotary engine, but it's a bit strange as it has two pairs of cylinders driving/driven by two cranks - but the diagram is so simplified that it does not show how the intake and exhaust are provided and whether it was air or water cooled.
Hope this helps, but it needs a longer explanation with diagrams really.
