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 a written contract with B, executed by A on behalf of X, is signed by A in such form as to bind him personally, the question of the right of the parties to the contract to show that A was the agent of X and that such contract was intended to bind X, depends on the nature of the contract and the purpose for which A's agency is to be shown. If B sues on the contract and A seeks to show that he was agent and X was principal in order to avoid liability, such evidence is inadmissible.1 If A signs his own name, without any addition thereto suggesting agency, the only effect of evidence showing A's agency and thereby relieving A from liability would be to contradict the terms of the contract. This rule applies alike to negotiable contracts such as notes2 and drafts, so that the agency of an indorser who signs his individual name cannot be shown to relieve him,3 and to non-negotiable contracts,4 such as a contract of sale,5 a contract of warranty,6 or a contract on behalf of corporation to be formed, signed so as to bind the promoters individually.7
2McPherson v. Weston, 85 Cal. 90; 24 Pac. 733; Scammon v. Adams, 11 111. 575; Armstrong v. Bank, 90 Ky. 431; 9 L. R. A. 553; 14 S. W. 411.
3Hazzard v. Duke, 64 Ind. 220.
4 Shaw v. Jacobs, 89 la. 713, 719; 48 Am. St. Rep. 411; 21 L. R. A. 440; 55 N. W. 333; 56 N. W. 684.
5 Syracuse Third National Bank v. Clark, 23 Minn. 263; United States National Bank v. Geer, 55 Neb. 462; 70 Am. St. Rep. 390; 41 L. R. A.
444; 75 N. W. 1088; reversing on rehearing, 53 Neb. 67; 41 L. R. A. 439; 73 N. W. 266.
6 United States National Bank v. Geer, 55 Neb. 462; 70 Am. St. Rep. 390; 41 L. R. A. 444; 75 N. W. 1088; reversing on rehearing 53 Neb. 67; 41 L. R. A. 439; 73 N. W. 266.
1 American Alkali Co. v. Bean, 125 Fed. 823; Vail v. Ins. Co., 192 111. 567; 61 N. E. 651; Hancock v. Fairfield, 30 Me. 299.