A fire alarm system warns people when smoke, fire, carbon monoxide or other fire-related emergencies are detected. These alarms may be activated automatically from smoke detectors and heat detectors or may also be activated via manual fire alarm activation devices such as manual call points or pull stations. Alarms can be either motorized bells or wall mountable sounders or horns. They can also be speaker strobes which sound an alarm, followed by a voice evacuation message which warns people inside the building not to use the elevators. Fire alarm sounders can be set to certain frequencies and different tones including low, medium, and high, depending on the country and manufacturer of the device. Most fire alarm systems in Europe sound like a siren with alternating frequencies. Fire alarm electronic devices are known as horns in the United States and Canada and can be either continuous or set to different codes. Fire alarm warning devices can also be set to different volume levels.
Bristol (/ˈbrɪstəl/ (About this soundlisten)) is a city, ceremonial county and unitary authority in England. Situated on the River Avon, it is bordered by the ceremonial counties of Gloucestershire, to the north; and Somerset, to the south. Bristol is the most populous city in South West England. The wider Bristol Built-up Area is the eleventh most populous urban area in the United Kingdom.
Iron Age hill forts and Roman villas were built near the confluence of the rivers Frome and Avon, and around the beginning of the 11th century, the settlement was known as Brycgstow (Old English "the place at the bridge"). Bristol received a royal charter in 1155 and was historically divided between Gloucestershire and Somerset until 1373 when it became a county of itself. From the 13th to the 18th century, Bristol was among the top three English cities, after London, in tax receipts; however, it was surpassed by the rapid rise of Birmingham, Manchester and Liverpool in the Industrial Revolution.
Bristol was a starting place for early voyages of exploration to the New World. On a ship out of Bristol in 1497 John Cabot, a Venetian, became the first European to land on mainland North America. In 1499 William Weston, a Bristol merchant, was the first Englishman to lead an exploration to North America. At the height of the Bristol slave trade, from 1700 to 1807, more than 2,000 slave ships carried an estimated 500,000 people from Africa to slavery in the Americas. The Port of Bristol has since moved from Bristol Harbour in the city centre to the Severn Estuary at Avonmouth and Royal Portbury Dock.
Bristol's modern economy is built on the creative media, electronics and aerospace industries, and the city-centre docks have been redeveloped as centres of heritage and culture. The city has the largest circulating community currency in the UK; the Bristol pound, which is pegged to the Pound sterling. The city has two universities, the University of Bristol and the University of the West of England, and a variety of artistic and sporting organisations and venues including the Royal West of England Academy, the Arnolfini, Spike Island, Ashton Gate and the Memorial Stadium. It is connected to London and other major UK cities by road and rail, and to the world by sea and air: road, by the M5 and M4 (which connect to the city centre by the Portway and M32); rail, via Bristol Temple Meads and Bristol Parkway mainline rail stations; and Bristol Airport.
One of the UK's most popular tourist destinations, Bristol was named the best city in Britain in which to live in 2014 and 2017, and won the European Green Capital Award in 2015.