Abstract: A hydraulic earth leveling machine has a pair of legs, and cross pieces to connect the legs together. The hydraulic earth leveling machine is attached to a ladder by clamps on the cross pieces. The legs of the hydraulic earth leveling machine telescope; and, as long as there is the weight of the ladder only, the legs freely telescope so the ladder can be set vertically regardless of the slope or obstacles of the terrain. Fluid cylinders within the legs move freely with only the weight of the ladder, the fluid flowing back and forth between the two cylinders to allow motion of the two legs. When additional weight is added to the weight of the ladder, fluid pressure causes control valves to close and prevent fluid flow from either fluid cylinder, so the hydraulic earth leveling machine is locked and stable. The legs have feet that grip the ground to assist in stabilizing the ladder.

Abstract: A seismically triggered valve is designed to shut off gas supply during an earthquake. A valve member is pivoted within a valve body, the valve member being mechanically movable to the open position by a plunger. A magnet is fixed to the valve member, and a ferromagnetic ball is free on a concave surface. The center of the concave surface is aligned with the magnet; but, when the valve is shaken the ball moves and releases the magnet. Gravity moves the valve member to the closed position, and the valve member is held in the closed position by magnetic attraction.