Nkolaus Otto, aided by Eugen Langen, had…

Nkolaus Otto, aided by Eugen Langen, had developed the noisy but well-received Otto and Langen engine in 1866, a free piston atmospheric engine (the explosion of gas is used to create a vacuum and the power comes from atmospheric pressure returning the piston).

The principle of operation had been described by the Italian inventors Eugenio Barsanti and Felice Matteucci in their British Patent no. 1625 of 1857, although they had never produced a marketable example.

Their improved engine is awarded the Grand Prize at the 1867 Paris World Exhibition.

It consumes less than half the gas of the Lenoir and Hugon engines and so is a commercial success.