Consisting of four 18″(45 cm) long wooden blocks each with Ten inset Knobbed cylinders graded in height and or diameter.
In block No.1 – the cylinder increases in both height and diameter.
In block No.2 – Cylinder increases in diameter but remain constant in height.
In block No.3 – Cylinder decreases in height but increases in diameter.
In block No.4 – Cylinder increases in height while diameter remains constant.
