Course and distance vs. natural objects

It is undoubtedly the practice of surveyors, and the practice was proved in this cause, to express in their plats and certificates of survey, the courses which are designated by the needle; and if nothing exists to control the call for course and distance, the land must be bounded by the courses and distances of the patent, according to the magnetic meridian. But it is a general principle that the course and distance must yield to natural objects called for in the patent. All lands are supposed to be actually surveyed, and the intention of the grant is to convey the land according to that actual survey; consequently if marked trees and marked corners be found conformably to the calls of the patent, or if water-courses be called for in the patent, or mountains or any other natural objects, distances must be lengthened or shortened, and courses varied so as to conform to those objects.