Model of a trunk engine, John Penn, Petrus van der Loo, 1855
The trunk engine, invented by the British engineer John Penn, greatly improved steam propulsion for ships. Penn’s use of a ‘trunk’, or cylindrical case, housing a connecting rod, instead of a beam or side lever, made the engine more compact and allowed it to be installed horizontally across a vessel’s keel. A number of Dutch naval ships were fitted with the trunk engine. This model represents a 150 h.p. engine.