THE FOUR BRISTOL JUPITER ENGINES of the Imperial Airways liner Scylla. At a height of 5,000 feet these air-cooled radial engines develop a maximum of 600 horse-power each at 2,200 revolutions a minute. Each engine is mounted in the font of a metal nacelle which is supported by two vertical tubes, one at the front and one at the back. An oil tank for each engines is contained in the streamline nacelle behind the engine; each tank holds sixteen gallons. The petrol tanks, of which there are three, are in the centre section of the upper plane; these tanks feed petrol to the engines by gravity. The total capacity of the petrol tanks is 720 gallons. The Scylla has a cruising speed of approximately 105 miles an hour at 5,000 feet.