THE DRAWING IS LINED FOR VARYING SHADES OF THE COLOR BLUE. WHERE THE LINES ARE RELATIVELY CLOSE TOGETHER THE SHADE IS DARKER THAN WHERE THE LINE ARE SPACED FURTHER APART. THE DARKEST SHADES ARE AT THE BOTTOM OF THE DRAWING, AND FROM THERE THE SHADE PROGRESSIVELY LIGHTENS AS THE TOP IS APPROACHED. HOWEVER, COLOR IS NOT CLAIMED AS A FEATURE OF THE MARK.