Scientific, nautical, surveying, optical, weighing, measuring, signaling and checking or supervision apparatus and instruments and computer software for use therewith, namely, ultrasonic thickness gauges used to determine the thickness of all metal types and of engineered plastics, through coatings and to test for wear, flaws and weaknesses in engineered plastics; scientific, nautical, surveying, optical, weighing, measuring, signaling and checking or supervision apparatus and instruments and computer software for use therewith, namely, ultrasonic leak detectors used to pinpoint air leaks in pressure and vacuum systems, along pipes, valves, flanges and gaskets, to detect mechanical wear of bearings, bushes or shafts in motors and pumps, to locate bad or leaking steam traps, to check for leaks on hydraulic or pressurized liquid systems, to find boiler and heat exchanger leaks, to detect arcing and sparking in electrical circuits, to find leaks in tanks, vessels, hatch covers, water tight doors and windows, to locate leaks on vehicles from inside car bodies to air brake and pneumatic systems, to inspect turbines, vacuum chambers or compartments of electric generators and nuclear reactors for leaks; scientific, nautical, surveying, optical, weighing, measuring, signaling and checking or supervision apparatus and instruments and computer software for use therewith, namely, ultrasonic emulsion, oil and solution analyzers for use in the food, drink, personal and beauty care products and pharmaceutical industries for the characterization of solutions, emulsions, and other complex liquids and soft-solids and for general purpose ultrasonic velocimetry; electronic apparatus and instruments for gauging thickness of ship's hulls, storage tanks and pipelines; electronic apparatus and instruments for detecting leaks, metal thickness and wear in ship's hulls, storage tanks, pipelines, anchor chains, jetties, dock gates, piers and pilings and bridges; electronic apparatus and instruments for measuring velocity, namely, for measuring ultrasonic velocity of partially crystalline materials to determine their solid content; and replacement parts for all the aforesaid goods