Abstract: An apparatus comprises a vertically extending receiving hopper (1) having a guide funnel (2) in the bottom part thereof. A disk (3) having at least one discharge opening (4) is mounted between them. Above the discharge opening (4) is mounted a cut-off member (9) with a possibility of vertical and horizontal movement and has its surface extending in parallel with the disc (3) surface.

Abstract: A reversible air-operated percussive action machine for driving holes in the ground has a housing accommodating a hammer 2 capable of reciprocating therein. An air distributor 3 is arranged in the hammer 2 in the form of a fixed tube 12 and a valving member 13 movable relative to the tube. Defined between the tube 12 and valviong member 13 is an accumulating chamber 18 which communicates with an air feeding line 4. An air restrictor is further provided for discharging air from the accumulating chamber 18 when the supply of compressed air to the air feeding line is terminated. The valving member 13 spring-loaded relative to the tube 12 by a spring arranged so that during feeding compressed air to the accumulating chamber 18 the valving member 13 is acted upon by a pressure force directed counter to the action of the spring.

Abstract: A deformograph comprises a sensitive element shaped as a tube of an optically sensitive material and fixed in a borehole by cementing the gap between said tube and walls of the borehole. One end of the tube is tapered off and provided with a specular coating, while the other end thereof has a specular coating with transparent sections. There are also provided a polarized light source furnishing a light signal transmitted through the material of the tube, and a sensing unit designed to pick off from the sensitive element a useful light signal indicative of the changing condition of the earth's crust in a given area.