For all future surveys governing city elevations, a datum plane of mean sea level as established by the United States Geological Survey for the years 1905 to 1910, inclusive, is hereby adopted, and the Geodetic Survey Bench and aluminum tablet stamped “449 B-1903” on University of Oregon grounds on the northeast corner front face of Villard Hall, the precise elevation of which is 449.317, is adopted and accepted as the controlling bench mark for the city.