Built at Bristol by Brazil-Straker under the direction of Roy Fedden, the Mercury featured an unusual crankshaft and connecting rod arrangement that dispensed with the more normal design of a single master rod linking to individual rods for each cylinder. It was said to run well without vibration and set an unofficial time to climb record while fitted to a Bristol 21A Scout F.1, the aircraft achieving 10,000 ft (3,000 m) in 5.4 minutes and 20,000 ft (6,000 m) in 16.25 minutes.[1]
An Admiralty order for 200 engines was placed in 1917 but was later cancelled by Lord Weir due to the end of World War I, it is also stated that Lord Weir had a preference for the ABC Dragonfly.[2]
The name was re-used by Fedden for the later nine-cylinder Bristol Mercury radial engine.