A fireman, stoker, or watertender is a person whose occupation it is to tend the fire for the running of a boiler, heating a building, or powering a steam engine. Much of the job is hard physical labor, such as shoveling fuel, typically coal, into the boiler's firebox. On steam locomotives, the title fireman is usually used, while on steamships and stationary steam engines, such as those driving saw mills, the title is usually stoker (although the British Merchant Navy did use fireman).

Source: Wikipedia