Some writers use the term interchangeably with monotube boiler[1] and there is even use of the term semi-flash boiler.[2] However, the flash boiler is generally attributed to Léon Serpollet who used a flash boiler in the Gardner-Serpollet steam-powered car from 1896. Serpollet's boiler was a low-water-content type with thick-walled tubes to provide a store of heat. Serpollet patented a steam generator in 1888, US Patent 379,421,[3] but this is an early version which differs from the one illustrated above.