For the purposes of this Part of this Act, a person shall not be taken to weigh or otherwise measure or count any goods in the presence of any other person unless he causes any equipment used for the purpose to be so placed, and so conducts the operation of weighing or otherwise measuring or counting the goods, as to permit that other person a clear and unobstructed view of the equipment, if any, and of the operation, and of any indication of quantity given by any such equipment as the result of that operation.