Acoustic pulse generator

Apparatus for generating an acoustic pulse medium comprising:

• (a) a hollow cylindrical housing having a closed top and open bottom adapted to be supported in an upstanding position, the upper portion the bore of said housing being tapered in the direction of said closed top, said tapered portion being penetrated by a plurality of large area ports communicating with the exterior of said housing,
• (b) means connecting said ports with a source of compressed gas,
• (c) an impact piston movable within said housing and having a tapered upper portion adapted to mate with said tapered portion of said bore in the ready position of said piston and thereby to cover the entrance to said ports, a component of force of said compressed gas being thereby exerted continuously in a downward direction on said tapered portion of said piston.
• (d) means for supporting said piston in said ready position,
• (e) means mounted on the wall of said bore adapted to be sealingly engaged by the tapered portion of said piston in said ready position to prevent said compressed gas from entering said bore,
• (f) a target positionable adjacent the lower end of said housing, and
• (g) means for quickly removing said support means whereby said compressed gas is enabled to drive said piston downwardly to deliver a blow to said target.