Simple 'spring' balance

Punch four holes in an old tin lid with a nail, spacing them partially round the circumference. Pass pieces of string by these holes and tie them together. Now join this scale.

If weights are not available, it is possible to graduate the balance using known volumes of water poured from a calculating jar and by making marks on the supporting stick conflicting the edge of the pan. Stones canthen be found which will give the similar extension and these should be marked for future use as weights. The use of coins for this purpose should also be investigated.