Noun
Cornish engine (plural Cornish engines)
A kind of beam engine used mainly for pumping water from mines. A heavy pump rod or plunger, raised by the steam, forces up the water by its weight in descending.
The Cornish engine was developed by Trevithick and others in the 1810s. Source: Internet
The Cornish engine had irregular motion and torque though the cycle, limiting it mainly to pumping. Source: Internet