The aim of some contractors, once they start work on a contract, is to have some change made from the plan as originally drawn, so the contract cannot be lived up to, and the work then becomes a sort of day affair for which they can charge whatever they please. To guard against such individuals, as well as to be prepared for any emergency, it is well to insert a clause in the specifications stating just what effect a change from the original plans will have on both parties to the contract, and reciting what forms will be observed in case it is found necessary to deviate from the work as originally planned. It is well to always require that the contractor shall have a written order authorizing him to do extra work, without which any claims for extras will be ignored and payment for such claims refused, and the means for determining the cost of extra work should be specified in case of a disagreement between the contractor and owner or architect should arise. A good provision is to specify that* in case of a disagreement between the contractor and owner, or contractor and architect, as the case might be, a third person who should also be named shall decide; or else, that the cost shall be determined by arbitration, if an arbitration clause has been incorporated in the specifications.