engine. The vertical cylinder is not water cooled. There is a central exhaust port on the cylinder wall uncovered by the piston. Separate gas and air pumps operates at twice engine speed to deliver the fresh charge to either end of the cylinder and purge the cylinder of exhaust gases, but the piston compresses the charge once the exhaust port is covered. Dugald Clerk describes several patents on the internal combustion engine between 1839 and 1854, but states that "Of these patents, by far the most important is Barnett's". Praise indeed from an eminent engineer who would subsequently receive a KBE and become a fellow of the Royal Society. The concept of a two-stroke double acting gas engine was later taken up by Körting who launched a 350bhp engine based on this principle in 1900. It was in production for many years. Heat management required a water cooled cylinder and piston. The air pump system was arranged so that air was admitted before gas/air mixture thus improving scavenging, and a longer piston meant less of the stroke was available for the scavenging to take place. Mechanical valve operation was used on the inlet valve and on control valves for the air and gas pumps. Further details can be found in the literature. See also History of the internal combustion engine Lemuel Wellman Wright who constructed and patented a non-compression gas engine of similar layout in 1833 References 1802 births 1865 deaths British inventors Engineers from Bradford People associated with the internal combustion engine