What was the first warning siren?

The first siren was invented by John Robison towards the end of the 18th century as a device to create a piercing sound. The noise is generated by a jet of air being forced through a high-speed rotating disc with evenly spaced holes around its edge.
How far can you hear a tornado siren?
Outdoor warning sirens are designed to be heard and alert people outdoors to go indoors and receive weather updates from local media. Outdoor sirens can be heard for approximately 1 mile in each direction. However, rain, wind and hail and other factors may affect your ability to hear the sirens.