Before the Great War, around 1905 they built a two-stroke, four-cylinder, radial engine at 90°. Its characteristic is that the connecting rods and pistons are rigid and crank pin slides along an elongated hole at the foot of the two connecting rods which are opposed and joined at this point.

"System diagram"

-This is the La Hire operating principle: under the working face A, there is a second chamber B in tandem formed by the bottom of the piston where a pre-mixture-pressure is created and prepares it to enter A.

"Berthaud engine"

-Associated with Prini they built the water-cooled, inline, 4-cylinder engine with the same operating principle. (See Prini et Berthaud)).

"Motor Berthaud -et Prini"

From appendix 6: We have a new picture of an engine of this type. It has four cylinders in X with rigid rods and a slotted hole in the center of them to allow rotation of the crankshaft.

-It has 4 cylinders and delivers 50-60 CV.

"Nice view of the Berthaud X engine with propeller"