A beam balance is a device used to measure mass. An object is put into a disk on one side that hangs from one end of a bar. It is balanced with weights at the other end. It has a lever at the middle just for support with two equal arms and a pan suspended from each arm at the end of the beam by equal length of strings. More so it can be used to measure various object.it is a very useful machine . it is used by shopkeepers to weight the material which the customer is buying.