Haycock boiler

A haycock boiler is an early form of steam locomotive boiler with a prominently raised firebox of "Gothic arch", "haystack", or "coppernob" shape. The term haystack is most commonly used, but is avoided here as it is confusingly used for three quite different forms of boiler. This particularly large outer firebox served as the steam dome and was often highly decorated with polished brass. These were popular for early railway locomotives, from 1840 to the 1850s.