A lawful fence shall be of at least four barbed, horizontal, well-stretched wires, spaced so that the top wire is forty-eight inches, plus or minus four inches, above the ground and the other wires at intervals below the top wire of twelve, twenty-two, and thirty-two inches. These wires shall be securely fastened to substantial posts set firmly in the ground as nearly equidistant as possible, but not more than twenty-four feet apart. If the posts are set more than sixteen feet apart, the wires shall be supported by stays placed no more than eight feet from each other or from the posts.