The stone, the surface of which is 12 inches each way and so champered or beveled as to leave a horizontal surface on top four inches square and perpendicular length of which is three feet, and which was set by R.H. Smithwick, City Engineer, on June 2, 1891, as described in his report thereof and the location of which is 12 feet south of the north side of Oklahoma Avenue, measuring from the north line of the avenue to the south side of the stone and eight feet east of the west line of First Street, west of Division Street, measuring from the west line of the street to the east line of the stone shall be and the same is hereby established as a permanent city bench mark; and the elevation of the top of the stone or bench mark is declared to be 143.50 feet above an assumed datum plane; and the elevation of all street grades, curbing, paving, water mains and laterals, sewer mains and laterals, shall be determined with reference to the datum plane. In all ordinances referring to streets, curbing and paving grades, or the elevations or grades of water mains and laterals and sewer mains and laterals where elevations or vertical distances shall have reference to the datum plane and elevations or given in feet shall signify so many feet above this datum plane unless otherwise expressed.
(`90 Code, § 19-29)