Watt steam engine — A late version of a Watt double-acting steam engine, built by D. Napier & Son (London) in 1859, now in the lobby of the Superior Technical School of Industrial Engineers of the UPM (Madrid). Steam engines of this kind propelled the Industrial Revolution in Great Britain and the world.
Photo Credit: By Nicolás Pérez, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=195711