Abstract: A mining machine adapted to traverse a mine face comprises a rotary drum, which may be mounted transversely or forwardly of the machine body, carrying liquid orifices which are supplied with water under pressure so that each orifice produces a water jet of continuously varying pressure which is directed at the material being mined at least for some of the times when the jet pressure is at its maximum value. In operation, reciprocation between a number of pistons and respective bores, the bores being formed in the drum, is brought about as the drum rotates by an eccentric bearing with which the pistons coact. The drum may carry cutting picks to assist the water jet cutting.