At sea , septentrional , by night the polestar , located at the point of intersection of the right line from beta to alpha in ursa major produced and divided externally at omega and the hypotenuse of the rightangled triangle formed by the line alpha omega so produced and the line alpha delta of ursa major 将大熊星座的“贝塔阿尔法”这一直线延长至星座外的“奥墨伽” ，北极星便位于“阿尔法奥墨伽”这道外部区分线与大熊星座内的“阿尔法德尔塔”这一直线所形成的直角三角形斜边的交点上340 。
