Petterson, of whose last will and testament, the plaintiff is the executrix (P), was the owner of a parcel of real estate in Brooklyn. Pattberg (D) was the owner of a bond executed by Petterson which was secured by a third mortgage upon the property. On April 4, 1924, the sum of $5,450 remained unpaid. This amount was payable in installments of $250 on April 25, 1924, and upon a like monthly date every three months thereafter. There was still five more years to run before the entire sum became due. Under the date of the 4th of April 1924, D wrote Petterson as follows: 'I hereby agree to accept cash for the mortgage which I hold against premises 5301 6th Ave., Brooklyn, N. Y. It is understood and agreed as a consideration I will allow you $780 providing said mortgage is paid on or before May 31, 1924, and the regular quarterly payment due April 25, 1924, is paid when due.' On April 25, 1924, Petterson paid D the installment of principal due on that date. A day in the latter part of May 1924, Petterson presented himself at D's home and knocked at the door. D demanded the name of his caller. Petterson replied: 'It is Mr. Petterson. I have come to pay off the mortgage.' D answered that he had sold the mortgage. D partly opened the door. Petterson exhibited the cash and said he was ready to pay off the mortgage according to the agreement. D refused to take the money. Prior to this, Petterson had made a contract to sell the land to a third person free and clear of the mortgage to D. Meanwhile, D had sold the bond and mortgage to a third party. Petterson had to pay the new owner the full amount of the bond and mortgage. P claimed that he thereby sustained a loss of $780, the sum which the defendant agreed to allow upon the bond and mortgage if payment in full of principal, less that sum, was made on or before May 31st, 1924. P has had a recovery for the sum thus claimed, with interest. This appeal resulted.