When a person sails or travels towards the equator, he is said to depress the pole; because as many degrees as he approaches nearer the equator, so many degrees will the pole be nearer the horizon. This phenomenon arises from the spherical figure of the earth.

DEPRESSION of a Star, or of the Sun, is its distance below the horizon; and is measured by an arc of a vertical circle, intercepted between the horizon and the place of the star.

DEPRESSION of the Visible Horizon, or Dip of the Horizon, denotes its sinking or dipping below the true horizontal plane, by the observer's eye being raised above the surface of the sea; in consequence of which, the observed altitude of an object is by so much too great.