The intense increase in the volume of construction is making the problem of creating effective methods and means of nonblasting fracturing of materials quite urgent.The Institute of Hydrodynamics, Siberian Branch, Academy of Sciences of the USSR, has conducted theoretical and experimental investigations into the creation of means of fracturing solid materials by high-pressure pulsed jets. The jetting method of fracturing has a number of virtues: there is no outlay for an expensive tool, since the rock is fractured by water; dust does not form, which eliminates silicosis; the implement does not contact the working face; pulsed jets act on the face with a high instantaneous power. However, the results of testing the water-jet propelling devices created at the Institute of Hydrodynamics showed that although the high-pressure pulsed jets can fracture strong rocks the energy-output ratio of fracturing depends on the strength of the rock and natural discontinuity of the mass, and the economically effective area of use of such jets does not extend beyond rocks of average strength, (Fig, i). In the water-jet propelling devices, by means of which the results of fracturing rocks being analyzed were obtained, the pressure in the impact chamber gradually increases, due to which shooting of the jet and its spontaneous damping occur. At the same time there are suggestions [i] which permit eliminating the unfavorable features of the water-jet devices of the given design, which apparently can introduce certain corrections in the conclusions about the effectiveness of using pulsed jets.