A superior and sturdy apparatus. A Borosil glass tube of about 30 cm Dia and one meter long is made to stand vertically firmly in between two upright bars with the help of clamps on a heavy cast iron base. Both sides of the tube are open. On the lower end a rubber cork without holes is fitted whereas on upper end a rubber cork with a funnel is provided. With two rubber band index mark and 6 steel balls of different diameter. Without lead shot