This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
If the collateral contract is inconsistent with the written contract, it cannot be enforced even if it is really collateral, and hence otherwise enforceable.1 Thus an oral contract, collateral to a written contract and changing the time fixed therein for performance, is unenforceable, as an oral contract to pay to the vendor of realty two hundred dollars on the execution of the written contract,2 an oral contract changing the time for making repairs where the written contract provided for making repairs and delivering possession at a specified time,3 an oral contract that a note, on its face payable generally, should be paid out of certain specified funds,4 or to credit on a note given, a sum in the event of the breach of another contract,5 or an oral contract to conform to usage as to payment under a written building contract, where, no time for payment being specified, the payment was in legal effect due only on completion of the building.6 So one who signs a note as surety cannot show an oral contract whereby the maker agreed to take a mortgage from the principal debtor as further security and to enforce such mortgage before proceeding against the surety.7 So an oral agreement that the vendor will procure and file for record a patent for certain land which he has contracted to sell by written contract, within sixty days from the date of such contract, cannot be enforced where the contract merely requires the vendor to furnish a good abstract and a warranty deed.8 An alleged collateral contract is as unenforceable when inconsistent with the legal effect of the written provisions as when it is inconsistent with express provisions. Under a written contract of sale, the legal effect of which was to pass title upon delivery, a collateral oral contract that the vendee should test the property sold before accepting it, and before acquiring the title, was unenforceable.9 So under a written contract the effect of which is to make a separate complete sale of each installment as delivered, an oral contract providing for redelivery in the event of failure to pay for subsequent installments cannot be enforced.10 Where A made a contract with B, whereby A was to make application for, and if possible obtain, letters patent for "certain new and useful improvements in hat pouncing, or finishing machines," in certain countries, in consideration of five thousand five hundred dollars to be paid by B to A, B could not show an oral agreement that future improvements were included in addition to those already made by A, nor could he show that the money was to be paid by him only if the improvements made the machines able to pounce hats in the English method.11
11McEnery v. MeEnery, 110 la. 718; 80 N. W. 1071.
12McTague v. Finnegan, 54 N. J. Eq. 454; 35 Atl. 542.
13 Sutton v. Lumber Co. (Ky.), 44 S. W. 86.
14McAleer v. United States, 150 U. S. 424.
15 Zanturjian v. Boornazian, -E. 1. -; 55 Atl. 199.
16 Rutter v. Ins. Co., 138 Ala. 202; 35 So. 33.
17 Brantingham v. Huff, 174 N. Y. 53; 95 Am. St. Rep. 545; 66 N. E. 620.
1 Keith v. Parker, 115 Fed. 397; Adams v. Turner, 73 Conn. 38; 46 Atl. 247; Younie v. Walrod, 104 la. 475; 73 N. W. 1021; Kracke v. Ho-meyer, 91 la. 51; 58 N. W. 1056; Tripp v. Smith, 180 Mass. 122; 61 N. E. 804; Phelps v. Abbott, 114 Mich. 88; 72 N. W. 3; Rooney v. Koenig, 80 Minn. 483; 83 N. W. 399; Daggett v. Johnson, 49 Vt. 345; Hunter v. Hathaway, 108 Wis. 620; 84 N. W. 996.
2 Walker v. Mack, 129 Mich. 527; 89 N. W. 338.
3 Tripp v. Smith, 180 Mass. 122'; 61 N. E. 804.
4 Keith v. Parker, 115 Fed. 397.
5 Phelps v. Abbott, 114 Mich. 88;
72 N. W. 3.
6Riddell v. Ventilating Co., 27 Mont. 44; 69 Pac. 241.
7 Anderson v. Matheny, - S. D. -; 95 N. W. 911.
8 Younie v. Walrod, 104 la. 475;
73 N. W. 1021.