1940s: A hand draws vertical lines on a geometric shape with a pencil and a triangular ruler that follow points of a circle drawn on top of the geometric shape.
1940s: A hand draws vertical lines on a geometric shape with a pencil and a triangular ruler that follow points of a circle drawn on top of the geometric shape.
1940s: A hand draws vertical lines on a geometric shape with a pencil and a triangular ruler that follow points of a circle drawn on top of the geometric shape.