From the need of the boiler of a steam locomotive to exceed a minimum amount of pressure (See head (“buildup of fluid pressure”), also pressure head.) before the locomotive could start moving.
Head-of-steam Sentence Examples
bank of the Tombigbee river, at the head of steam navigation, 150.
But between 1900 and 1905 contracts were signed for the construction of three highways, leading respectively from Matagalpa, from Nueva Segovia and from the Pis Pis mining district to the head of steam navigation on the Segovia, about 160 m.
ill-suited scheme gaining too much of a head of steam.
There's a great head of steam pushing for new nukes around our coastline.
To get up a good head of steam the poor fireman would need to shovel coal into the firebox for all he was worth !