| Answer | Crossword Clue |
|---|---|
| magnetometer | An instrument used for measuring magnetic forces, esp. the earth's magnetism |
| magnetometers | An instrument used for measuring magnetic forces, esp. the earth's magnetism |
| gradiometer | An instrument for measuring the gradient of an energy field, esp. the horizontal gradient of the earth's gravitational or magnetic field |
| gradiometers | An instrument for measuring the gradient of an energy field, esp. the horizontal gradient of the earth's gravitational or magnetic field |
| variometers | An instrument for measuring variations in the intensity of the earth's magnetic field |
| variometer | An instrument for measuring variations in the intensity of the earth's magnetic field |
