An inclinometer measures tilt relative to the vertical established by gravity, usually reporting an angle from the perpendicular horizontal plane. A weighted-string inclinometer compares a sighting tube with a freely hanging reference; its scale must be oriented so a level sight gives zero altitude. A raw protractor may instead indicate the complementary angle, so check the markings rather than assuming that every instrument has the same scale. [ref]
https://www.exploratorium.edu/snacks/height-sight. Exploratorium Teacher Institute: Height Sight, gravity reference and angular readout
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An inclinometer, also known as a tilt sensor or tilt meter, is a device used to measure the angle of tilt or inclination of an object relative to a reference plane, typically the vertical or horizontal plane. Inclinometers can be used in various applications across multiple fields, including: 1. **Geotechnical Engineering**: To monitor the stability of slopes, embankments, and structures, ensuring they do not tilt dangerously or shift in position.