Several advances in the technology of fog signals were made during the 1850s. In 1851, an experimental air fog whistle and reed horn was installed at Beavertail Lighthouse at the entrance to Narragansett Bay, Rhode Island. At first this sound signal was powered by a horse-operated treadmill and later by an internal combustion steam engine. Around 1851, mechanically rung fog bells were introduced. The striking mechanism was governed by a weight attached to a flywheel, and later internally run by clockworks. The strokes of the fog signals were timed deliberately to afford each signal a unique sound characteristic. The bell signal was gradually replaced by three variations of that instrument. The first was an ordinary locomotive whistle, enlarged and modified and blown by steam from a high-pressure tubular boiler. The second was a reed-trumpet, and in 1866 the third variation, a siren-trumpet. Although the fog bell signal was still used for warning vessels over short distances, other fog signals started to supersede the smaller bell signal. Bells were also used on buoys; later whistling buoys were invented by J. M. Courtenay and were first in use in 1876. The first gas-lighted buoy was installed in 1882. The gong buoy was invented in 1923.