Gyroscopes; Seismographs; Tachometers; Azimuth instruments; Compasses for measuring; Directional compasses; Distance measuring apparatus; Electric coils; Electric navigational instruments; Electric sensors; Electrical transducers; Electro-optic transducers; Electronic coils; Global positioning system (GPS); Magnetic and electromagnetic coils; Marine depth finders; Measuring apparatus, namely, angle finders; Navigational instruments for vehicles; Optical sensors; Optical position sensors; Photoelectric sensors; Pressure measuring apparatus; Satellite-aided navigation systems