Bromide print of Jacob Perkins' Uniflow Steam Engine

Bromide print, 6" x 8", mounted, of Jacob Perkins' Uniflow Steam Engine, 1827

This shows the high-pressure steam engine patented by Jacob Perkins in 1827 in which the flow of the steam is unidirectional, i.e., after acting on a first piston it is used on a second piston in a second cylinder, both single-acting. Hence this engine may be considered to be the precursor of the uniflow engine, which set high standards of thermal efficiency in reciprocating piston engines.