gradiometer
/ˌgreɪdɪˈɒmɪtə(r)/noun
1- a surveying instrument used for setting out or measuring the gradient of a slope坡度（测量）仪。
1.1
- Physics an instrument for measuring the gradient of an energy field, especially the horizontal gradient of the earth's gravitational or magnetic field【物理】（测量能量场, 尤指测量地球重力或磁场水平梯度的）梯度仪。