built by the merryweather fire engine company in greenwich, in 1888, the butler petrol cycle (first recorded use of the term) was a three-wheeled petrol vehicle. the rear wheel was directly driven by a /hp (466w) 600 cc (40 in; 2¼×5-inch {57×127-mm}) flat twin four-stroke engine (with magneto ignition replaced by coil and battery), equipped with rotary valves and a float-fed carburettor (five years before maybach), and ackermann steering, all of which were state of the art at the time. the engine was liquid-cooled, with a radiator over the rear driving wheel. speed was controlled by means of a throttle valve lever. the driver was seated between the front wheels.