Instead of using the uncertain-acting flame with the inconvenient speed limitations, Daimler invented and introduced in 1883 the so-called hot-tube ignition. This consisted of a metal or porcelain tube attached to the compression space of the cylinder in such a manner that the interior of the tube was in continual communication with the compression space. A gas flame, continually burning under the tube, maintained it at a glowing red heat, so that the mixed charge of air and gas, when compressed into the tube, became fully and effectively ignited. Experience showed that by a proper regulation of the temperature of the hot tube the ignition could be made to take place at any desired point in the compression, and thus the complicated, slow and uncertain slide flame ignition was replaced by a simple device, without moving parts, altogether satisfactory and reliable. The especial feature of the hot-tube ignition, however, was soon found to be the increased speed which it permitted. By its use the rotative speed could be increased eight to ten times over the older motor, and hence the weight could be reduced in nearly the same proportion. [Illustration: GOTTLIEB DAIMLER] This fact at once showed Daimler that the application of the internal-combustion motor to mechanically propelled vehicles had become a possibility, and that, with the use of hydro-carbon vapor as fuel, and the high-speed hot-tube motor, the petroleum automobile might become a practical possibility. He therefore severed his connection with the Otto Engine Works at Deutz, and returning to Cannstadt, near Stuttgart, his early home, he devoted his entire time and attention to the design of a light petroleum motor and motor vehicle. The result was the production, in 1885, of a motor-bicycle, in which the motor was placed directly under the seat, between the legs of the rider. The petroleum was drawn from a tank, the supply being regulated by the valve. The motor was first set in motion by lighting a lamp and turning the crank a few times, the discharge passing through the chamber into an exhaust-pipe. After the motor had been fully started, the vehicle was set in motion by moving a lever, which drew a tightening pulley against the belt, and so caused the power to be transmitted from the shaft pulley to the wheel pulley. Changes of speed were attained by using pulleys of different sizes, similar to the cone pulleys on a lathe. This machine was put into successful action at Cannstadt on November 10, 1885.