The legal principles which govern this case are well settled. If the creditor agrees with the principal debtor to extend the time of payment, without the knowledge and con sent of the surety, the effect of • such agreement is to discharge the surety. But it must be a valid agreement, such as can be enforced either at law or in equity. Of course it must be made upon a good consideration, or be under seal. Oxford Bank v
The true principle which must govern all cases of this sort must be, that in order to constitute a valid consideration the promise of the debtor must be to do something which he is not already bound by his note or contract to do, or the act done by him must be something that he was not thus bound to do. Upon this principle, the payment of a part of the debt after it has become due, or a promise to pay a part of it at some future time, is not a valuable consideration. Chit. Con. (7th Amer. ed.) 51.
In the present case the payment was not on the note in suit, but on another note of the plaintiff against Searle, to which the defendants were not parties * and the promise of Searle was to make payments monthly on other notes to which the defendants were not parties. But the payment was an act which Searle was already bound to do, and the promise to pay was no more
Exceptions overruled.