eemailsuf Abney Level For Surveying To measure lines on a particular slope, Vernier Caliper  (150 mm)

It is a survey instruments consisting of a spirit level and a sighting tube used to measure the angle of inclination of a line from the observer to the another line and An Abney level and clinometer, is an instrument used in surveying which consists of a fixed sighting tube, a movable spirit level that is connected to a pointing arm, and a protractor scale. An internal mirror allows the user to see the bubble in the level while sighting a distant target.