It is generally acknowledged that the engine as we know it, was invented by Nickolaus August Otto, a German inventor around 1866. There were chemists and engineers working on the theory of an engine as far back as the mid 18th century. It was in the early 1820's that chemists knew that certain gases mixed with air would explode. Inventors were working hard on how to harness that power. As early as 1791 John Barber had patented a crude gas turbine, intended to employ inflammable air for the purpose of procuring motion. In 1794 Robert Street actually suggested using the upstroke of a piston to draw in gases from tar or turpentine with a flame that would explode it. In 1804 a Frenchman called Phillipe Lebon d'Humberstein, patented a double-acting two-stroke engine running on illuminating gas, with ignition by electricity. In 1826 a London man called Samuel Brown built a 40 liter gas and vacuum carriage that climbed Shooters Hill in Woolwich under it's own power, watched by numerous spectators. The first major progress in the concept of the internal-combustion engine was in 1854. Two Italian inventors, Eugenio Bassanti and Felice Matteucci, patented a two-stroke engine, where the explosion took place beneath a free piston which imparted motion to a working piston attached to a track rod, which as it rose and fell, it turned a gear wheel. It was in an 1860 report about an engine designed by Lenoir, a non-compression gas engine that inspired Otto, who was aged 28, and working as a clerk in a Cologne shop, to develop an internal-combustion engine for use where steam power was impractical. Otto's first engine, developed with the help of his brother Wilhelm, was refused a patent as it was considered too similar to Lenoir's engine. An improved version of Otto's engine also failed to get a patent, due to it's similarity with the engine of Bassanti & Matteucci. It was on April 21st 1866 that Otto got his first patent for an engine. There was very little commercial success until 1872, when Otto's company, Gas-Motoren-Fabrik Deutz with Gottlieb Daimler as production manager, sales took off.