Added by Ranjeev Mishra on August 22, 2002 at 00:51:42:
Have an accurate stop watch and measure the time taken by a rough stone to reach the ground when dropped from the height. Then the height,
h = g/2 t^2
where g - acceleration due to gravity - 9.8 m/s^2 usually but needs to be checked in your area.
t - the time measured in the above fashion.