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.
To constitute an alteration the change in the language of the written instrument must have been made intentionally. If not intentional, it is not an alteration.1 Placing internal revenue stamps on the face of a shipping receipt is not the erasure or alteration of any part of such receipt or contract covered thereby.2 If a waiver of demand and notice and a guaranty of payment is affixed with a stamp, and by mistake is placed above the signature of an indorser who did not waive or guarantee, instead of over the signature of the one who did, this does not discharge such indorser.3 If by mistake an indorsement is canceled on the wrong note,4 or one who means to sign as surety signs in the place appropriate for a witness,5 the contract is not thereby discharged.
3 McMillan V. Hefferlin, 18 Mont. 385, 45 Pac. 540.
4 Pelton v. Lumber Co., 113 Cal. 21, 45 Pac. 12.
1 Illinois. Merritt v. Dewey, 218 III. 599, 2 L. R. A. (N.S.) 217, 75 N. E. 1066 [distinguishing, Ryan v. First National Bank, 148 111. 349 (sub nomine, Reilly v. First National Bank, 35 N. E. 1120), as a case in which the alteration affected. the liability of an assenting guarantor, and was, therefore, immaterial as to the principal debtor].
Iowa. Murray v. Graham, 29 la. 520.
Kansas. Edington v. McLeod, 87 Kan. 426, 41 L. R. A. (N.S.) 230, 124 Pac. 163.
Kentucky. Letcher v. Bates, 29 Ky. (6 J. J. Mar.) 524, 22 Am. Dec. 92;
Citizens' State Bank v. Johnson County, 182 Ky. 531, 207 S. W. 8.
Missouri Evans v. Foreman, 60 Mo. 449; Koons v. St. Louis Car Co., 203 Mo. 227, 101 S. W. 49.
New Jersey. Hunt v. Gray, 35 N. J. L. 227, 10 Am. Rep. 232.
South Carolina. Smith v. Smith, 27 S. Car. 166, 13 Am. St. Rep. 633, 3 S. E. 78.
Vermont. Barton Savings Bank & Trust Co. v. Stephenson, 87 Vt. 433, 51 L. R. A. (N.S.) 346, 89 Atl 639; Gray v. Williams, 91 Vt. lll, 99 Atl. 735.
2 Barton Savings Bank & Trust Co. v. Stephenson, 87 Vt. 433, 51 L. R. A. (N.S.) 346, 89 Atl. 639.
3 Edington v. McLeod, 87 Kan. 426, 41 L. R. A. (N.S.) 230, 124 Pac. 163.
In the foregoing cases there was no intent to make the alteration in question at all. The mistake was analogous to a mistake in execution.6 The principle has been extended to alterations which the party making them intended to make, but such intention was caused by mistake of fact as to some collateral material fact.7 If a holder, believing that an instrument is to be paid,8 or has been paid,9 cancels it, such cancellation is not such alteration as discharges it.
An alteration made through a mistake of law while attempting to accomplish some lawful purposes, has been held not to discharge the contract. An example of this is found where one wishes to transfer a negotiable instrument and attempts to do so by substituting the name of the indorsee for that of the original payee.10 If a guarantor by inadvertence signs his name in such a way as to indicate prima facie that he is an original promisor, the contract is not discharged thereby.11
1 Shaw v. Probasco, 139 Ga. 481, 77 S. E. 577; Murray v. Graham, 29 Ia. 520; Sloman v. Express Co., 134 Mich. 16, 05 N. W. 999; Rhoads v. Frederick, 8 Watts (Pa.) 448.
2 Sloman v. Express Co., 134 Mich. 16, 95 N. W. 999.
3 Gordon v. Bank, 144 U. S. 97, 36 L. ed. 360.
4 Brett v. Marsten, 45 Me. 401.
5 Fisher v. King, 153 Pa. St. 3, 25 Atl 1029.
6 See Sec. 251 et seq.
7 This is analogous in nature to mistake in inducement (Sec. 384), though its effects are different.
8 Novelli v. Rossi, 2 B. & Ad. 757.
9 Lowremore v. Berry, 19 Ala. 130, 54 Am. Dec. 188; Boulware v. State Bank, 12 Mo. 542.
l0 Horst v. Wagner, 43 la. 373, 22 Am. Rep. 255.
11 Wallace v. Jewell, 21 O. 8. 163, 8 Am. Rep. 48.
 
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