eration, the agreement can not be enforced against the party making the concession. He is at liberty to change his mind.

(d) In such changes as are mentioned in (b) and (c) the law will not inquire particularly as to the adequacy of the consideration, so long as a legal consideration may be shown to exist.

(e) An apparent exception to the above rules of construction is that in which the original contract provides for changes to be made in a specific manner, and without further consideration. Thus it is sometimes specified and agreed upon. that the character of the materials or the methods described in the original contract may be changed at the pleasure of the engineer or architect, without further consideration. In this case any change made consistent with this provision would not be regarded as a new contract, but simply as a sort of construction of the old agreement. Under such a clause, however, the law would not allow a gross injustice to be worked against the contractor in the way of violent changes which would greatly increase the cost of the work, and which evidently were not anticipated by the parties to the contract at the time it was signed.

(f) In all cases where changes have been made in a contract, if such changes involve an increase in the time required for performance, the date of completion of the work fixed by the original contract will be extended by the courts for a period sufficient to cover the additional time required for the changes made. This the courts will do whether such extension of time be provided for, either in the original contract, or in the subsequent agreement.

(g) It is customary to include in the original specifications a clause describing the manner in which all changes in plans and specifications may be made, and the compensation for the same determined. In this case changes in the contract must be made in accordance with such provision, and such

changes, when so made, are binding upon the contractor, whether he consent or not. They might operate, however, to release the bondsmen.

(h) All contracts, except those required by law to be in writing, whether sealed or unsealed, can be modified by oral as well as by written subsequent agreement, regardless of any provision to the contrary in the body of the original contract.

DISCHARGE OF CONTRACTS.

40. Methods of Discharge. Any contract entered into in any of the methods heretofore indicated may be discharged and the parties thereto freed from all obligations thereunder, in any one of the following ways: 1. By agreement. 2. By performance. 3. By impossibility of performance. 4. By operation of law. 5. By breach.

41. Discharge by Agreement. Any contract which has been entered into by mutual agreement may evidently by mutual agreement be dissolved. This may be done, (a) by

a waiver or cancellation, (b) by a substituted agreement between the parties, or of the contract, (c) by a condition in the contract itself.

(a) An agreement to discharge the contract must be supported by a consideration the same as any other agreement. The usual consideration in this case is the mutual release from liabilities under the original contract.

(b) A contract may be discharged by the substitution therefor of a new agreement, the consideration in this case being as before the mutual discharge of obligation under the previous agreement. This new agreement may be either oral or written, and it will serve to replace or rescind the previous agreement if such were the intention of the parties. This is

true whether the original agreement was a sealed contract or simply a parole agreement. If, however, the original contract was required by law to be in writing so must also the new contract which replaces it.

The rescission of the former contract may be implied, as where the terms of the latter agreement conflict with those of the old, the later agreement taking precedence and discharging the former. The intention to discharge the former, however, must be clearly implied from its being the only rational assumption in the premises.

The contract may be rescinded by the substitution of a new party to it in place of one of the original parties. This may be done only where all parties to the contract are agreed, this agreement being either express, or implied by subsequent

acts.

(c) The contract may contain a provision for its own discharge on the happening of some event or contingency. This contingency may be the nonfulfillment of some specific clause in the contract itself, or on the occurrence of some particular event, or on the exercise by one of the parties of an option to determine it. When the event transpires which forms the condition of the discharge, the contract is thereupon rescinded.

Engineering contracts sometimes contain a clause to the effect that the work may be stopped at any time with a specified notice at the option of the party paying for the same.

42. Discharge by Performance. The usual method of discharging a contract is by each party fully performing the duties prescribed for him in the agreement. In this case the performance by each party must be strictly in accordance with the terms of the contract.

In engineering work it is seldom that the work is done in all details strictly in accordance with the plans and specifica

tions, or with such plans as authoritatively modified by the engineer. While in law the contract requires a strict and full compliance with all the terms of the agreement, yet in equity a substantial compliance is accepted in place of a full and complete performance. Also in equity an imperfect compliance is often taken as a discharge of the contract subject to such damages as would equitably compensate for the degree of failure to fully and completely satisfy the agreement.

One of the essential requirements of the contract is the time specified for the completion of the work, when this is so named in the agreement. When no time limit is mentioned in the agreement, the element of time is not deemed to be of the essence of the contract, but performance will be required within a reasonable time. When a specific time or date is given for completion, a court of equity will examine as to whether the intent of the parties was to determine in a general way the time when performance was expected or whether such limit was intended to be a specific and essential part of the contract. If the former meaning is imposed no relief can be had in equity for nonperformance within the specified time.

43. Performance on Conditional Promises. In engineering contracts performance on the part of the owner is usually conditioned on a previous performance on the part of the contractor. On the other hand, the owner sometimes agrees to make payments, for instance, at specified stages of the work, in such a way that further performance on the part of the contractor may be conditioned on the making of such payments at the times specified. Performance may also be conditioned in various other ways, as after the lapse of a certain time, or upon the occurrence of a particular event or contingency which may be uncertain, or on the acts of a third party, or even on the will of the promisor. In this last case it is really no contract at all, so far as the promisor is concerned. That is to say, while he can enforce it against the other party,

Such a case as

the other party can not enforce it against him. this last is where one party agrees to do work to another's satisfaction. Here the party performing the work is wholly at the mercy of the party to be satisfied, and the plea of dissatisfaction relieves him from liability. Evidently no person should place himself thus at the mercy of another, unless he can rely implicitly upon the good faith of the other party.

A common instance of the operation of a "condition precedent" with reference to a third party is where a contractor binds himself to receive payments on a building or engineering work only on the certificate of the architect or engineer. Without such certificate which forms a "condition precedent" the owner is not obliged to make payment. Before the contractor can force the owner to pay him for his work, in the absence of such a certificate from the architect or engineer, he must be able to prove that the architect or engineer has acted fraudulently in withholding the certificate, or that he has acted under gross mistake, and in bad faith, or has negligently refused to honestly examine the work. As this is, of course, very difficult to establish, the refusal of the architect or engineer to give such certificate commonly acts as a bar to payment under the terms of the contract.

Also where the quality or quantity of the work to be done is, by the terms of the contract, to be left to the approval of a third person, such as the engineer, his decision in the premises is binding upon both the parties.

The agreement may be conditioned upon a notice being given to the promisor, as where the engineer is required to give notice to the contractor to begin work at a certain time. In this case the proof of having given such notice is necessary to the enforcement of the contract.

44. Discharge by Payment. The discharge of a contract by full payment of money due upon it requires no