Victorian illustration to download showing a picture of a hydraulic coal-cutting machine in a coal mine. It has been brought to the coal face by a railway track. Beside it a coal miner reaches for his pickaxe. This machine was invented to speed up the process of undercutting (also known as holing and kirving): the seam of coal was undercut to let the coal above fall down, thus saving effort. This machine, which was shown at the Paris International Exhibition of 1867, was said to be able to cut 12 yards in an hour.