witness post
n.— «As surveys progressed, various improvements were introduced to secure regularity and convenience of description, by the establishment of base-lines, meridians, and standard parallels, through certain permanent natural points, the mouths of rivers…and more recently the summits of mountains,…each of these mountain tops overlooking an immense area, and all constituting monuments and witness posts to endure for all time.» —“Report of the Commissioner of the General Land Office” Message from the President of the United States to the Two Houses of Congress at the Commencement of the Second Session of the Thirty-Sixth Congress (Washington) , 1860. (source: Double-Tongued Dictionary)