Impulse turbines change the direction of flow of a high velocity fluid or gas jet. They could be lit from the interior or placed in front of a gas jet. The MGM-51A was stabilized by flip-out fins, and controlled by hot gas jet reaction controls. The Gas Jet post office operated from 1868 to 1876. The resulting images revealed a gas jet approximately 330,000 light-years long. Young developed a ringed gas jet to heat temper the bamboo for his rods.