George Manby is most famous for his invention of the Manby Mortar – a device once used to rescue a lot of people from shipwrecks. He is also known as the father of the modern fire extinguisher, which in itself has also saved thousands of lives. Fire extinguishers actually predate Manby's invention. One of the earliest ones was designed in 1723 by Ambrose Godfrey. Godfrey's device consisted of a fire-extinguishing liquid and a chamber of gunpowder. When the attached fuses were lit, the gunpowder exploded and scattered the liquid. They were not widely used, although there is an account of them being used in a fire in London in 1729. Manby's 1818 invention was more efficient. He was inspired to invent a portable fire extinguisher after witnessing firemen's inability to fight fires on the top floors of buildings because they were difficult to get to. He designed a device containing potassium carbonate with the remaining space taken up by compressed air. When the device was activated, it allowed the air to rush out and spread the potassium carbonate over quite a range. The system could also be used with water, and was portable, allowing firemen to reach otherwise inaccessible areas. Manby's invention was soon replaced by a newer model. However, the use of compressed air formed the premise for new prototypes, with modern extinguishers using carbon dioxide as the pressurising agent in a similar way.