Any person who shall remove, displace or mutilate the range stones imbedded in the streets of the city shall be guilty of a misdemeanor; provided, that where it shall become necessary for the purpose of grading or paving the said streets, to remove or displace said range stones, such displacement or removal shall be done under the personal supervision of the engineer, and only in vertical lines, and the said range stones so displaced or removed shall be removed to a depth of not less than six inches (6") below the surface of said streets respectively. (1908 Code)