Importance

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Abstract

A wheeled, self-propelled tractor has a percussion tool or hammer mounted on its forward end and an impact transmitting means carried on the tractor below the hammer. In accordance with one aspect of the invention, the impact transmitting means comprises a metal frame having a strong rigid top plate that is struck by the hammer and a downwardly opening cavity in which wood timbers are mounted to transmit the impact from the plate to a cemetery marker. Repeated blows to the marker applied through the impact transmitting means will drive the marker into the ground until it is flush with the ground surface where it will not interfere with mowing. The frame is fastened on the vehicle by a suspension system that includes tension springs which keep the wood timbers in a horizontal plane but permit the frame to move downwardly each time it is struck by the hammer. In accordance with a second aspect of the invention, method and apparatus for generating seismic waves for sub-surface geophysical exploration are described in which a weighted impact hammer is guided along an elongated track against a shock-transmitting plate. In a first mode of operation for generating seismic P-waves, the track is oriented in the vertical direction and the hammer is permitted to fall by force of gravity against the impact plate which is disposed on the earth surface therebelow. In a second mode of operation for generating seismic shear waves, the track is oriented at a selected shear angle with respect to the earth surface and guides the falling hammer against the shock-transmitting plate which is least partially penetrates the earth surface.

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First Claim