Steam whistle

When the lever (10) is actuated (usually via a pull cord), the valve opens and lets the steam escape through the orifice.

Steam whistles are often used on buildings such as factories, universities, and similar places to signal the start or end of a work shift, etc.

[8] It is said that George Stephenson invented his trumpet after an accident on the Leicester and Swannington Railway where a train hit either a cart, or a herd of cows, on a level crossing and there were calls for a better way of giving a warning.

One account states that [driver] Weatherburn had 'mouthblown his horn' at the crossing in an attempt to prevent the accident, but that no attention had been paid to this audible warning, perhaps because it had not been heard.

Stephenson subsequently called a meeting of directors and accepted the suggestion of the company manager, Ashlin Bagster, that a horn or whistle which could be activated by steam should be constructed and fixed to the locomotives.

The whistle, which is in the Guinness Book of World Records, was powered by an air compressor during the 2010 concert due to the costs of maintaining and running the boiler.

10" diameter whistles were used as fog signals throughout the United States for many years,[17] until they were later replaced by other compressed air diaphragm or diaphone horns.

[82] A 20-inch diameter ring-shaped whistle (“Ultrawhistle”) patented and produced by Richard Weisenberger sounded 124 decibels at 100 feet.

[89] The whistle bells of multi-bell chimes used on ocean liners such as the RMS Titanic measured 9, 12, and 15 inches diameter.

[93] The Union Water Meter Company of Worcester Massachusetts produced a gong whistle[clarify] composed of three bells, 8 x 9-3/4, 12 x 15, and 12 x 25 inches.

Tests of small Ultrawhistles have not shown higher sound levels compared to conventional whistles of the same diameter.