The first siren, consisting of air forced through a disc with evenly-spaced holes spun to produce the noise, was developed in the late 18th Century by philosopher and physicist John Robison. The device was further modified for steam-powered use in lighthouses.
Despite being bombed by German zeppelins in WWI, British government officials debated the deployment of an air raid siren system, but finally had one developed and in frequent use during the nightly German bombings of WWII.
The ancient Greeks and Egyptians developed alarm functions on water clocks, and ancient Chinese had candle clocks performing the same function.
Early mechanical alarm clocks were developed as early as the 15th and possibly even 13th centuries. In the more modern era, American inventor Levi Hutchins developed a smaller household alarm clock in 1787 which could only ring at 4am, following Levi’s firm rule to always rise before the sun and pray. Sixty years later, Frenchman Antoine Redier patented the first adjustable alarm clock.
The first fire alarm which wasn’t simply people relaying fire information was a telegraph-based electric system developed for Boston in 1852. It was successful, though it depended on people staying in or near burning buildings long enough to operate the crank and alert the local fire department.
The United States and Canada use the multiple alarm fire (two-alarm fire, three-alarm fire, etc.) to indicate how many firefighting units and how much equipment should be sent to fight the blaze. The higher the number, the more people and equipment needed.
The original sirens belonged to Greek myth. These half-bird, half-woman creatures sang a song so beautiful that sailors were lured near, only to have their ships destroyed and lives lost.