Resonant pendulum for underground water prospecting

摘要

The resonant pendulum has a mass attached to a string or chain (7) which is held by the index finger (8) and thumb (9). In the telescope design, the mass has a metallic cylinder (6,16) is fixed by a screw (14) or a split pin (17) in the tube (5,15). The cylinder is provided with marks (11,12,13), or drillings (18,19,20) into which the pin is placed. Alternatively the cylinder (21) also with marks (25) has disc type reflectors (22,23) at either end, where the cylinder is secured by a fixing screw (24). The mass can be a set of cylinders having varying specific lengths and can be made of metal, plastics, ferrite or compound materials.