It is an unquestionable general rule, that where parties have entered into a contract in writing, they are presumed to have expressed their agreement truly, and cannot be allowed to add to, vary, explain or contradict it by parol testimony of stipulations previously or simultaneously made. The question is, does the present case form an exception to this rule. Where a writing has been executed by way of part performance merely of a parol agreement, it is said its incompleteness warrants the admission of extrinsic proof. This exception is familiarly illustrated where a chattel has been sold with a warranty not in writing, and a note given for the purchase money. In such case, the note does not merge the parol contract. [6 Ala. Rep. 146 ; 3 N. Hamp. Rep. 455; 8 Wend. Rep. 116.]
In McCulloch v. Girard, 4 Wash. C. C. Rep. 280, at the conclusion of a parol agreement, the defendant signed a paper promising in a general way to transfer certain shares of stock in a bank about to be organized, as soon as the books for that purpose should be opened. The court said it was a question of fact for the jury, whether the instrument was given in full execution of the parol contract, or in part only; “ that if it should turn out that it formed part of the agreement that such a paper should be given, or that a paper of that description was in the ordinary course of defendant’s business in respect to transactions of this nature, given by him; evidence of the parol contract will be proper, and will not violate any of the rules of evidence.” So where there is a writing importing a sale of personal property, or any other like instrument of transfer, it will not preclude the vendee from proving an agreement between him and the vendor contemporaneous with the instrument, and consistent with its terms, that the value of the property should be applied to the payment of the defendant’s debts. [5 Gill & Johns. R. 147, 157. See also, 6 Id. 107; 9 Pick. Rep. 338.] Parol evidence is said to be admissible to prove collateral and independent facts, about which the writing is silent. [1 Phil. Ev. 562, 563.]
*492The fact that the consideration which induced the making of the note is expressed upon its face, is not such a circumstance as conclusively indicates, that the writing is a complete expression of the contract of the parties. It serves to show what was the consideration, and dispenses with additional proof to this point. It proves what was the inducement to the making of the note, but does not set out what were the stipulations in respect to the work, or exclude the idea that there were any. The proof of the agreement then, on the part of the plaintiff, was independent of, and collateral to, the writing, and its admission consequently within the exception stated. The county court therefore erred in the exclusion of the testimony — its judgment is reversed and the cause remanded.