If this is an action of assumpsit, as claimed by the plaintiffs, they must prove the promise averred, by legal evidence. The Court are of opinion, that the promise relied on was not collateral to, and independent of, the written contract made between the parties, and which was considered in a former case ; Wakefield v. Stedman, 12 Pick. 562 ; but that it was part of the same contract, in the nature of a condition or defeasance, and as such cannot be set up and established by paroi proof.

Plaintiffs nonsuit.