Langen and Otto's patent, 1866, atmospheric or 'free piston' gas engine, No. 1, half hp, patented by Nikolaus August Otto and Eugen Langen, and made by Crossley Brothers, Manchester, England, 1869

This is the first atmospheric gas engine built to Otto and Langen's patent by Crossley Brothers of Manchester. Otto and Langen's atmospheric gas engine was the world's first commercially successful internal combustion engine, and Crossley were highly important in its diffusion into the wider world, holding the manufacturing rights for the whole world except for Germany. They built approximately 1,300 atmospheric engines starting in 1869.