In some instances, particularly in the sale of vacant lots, it is found that the purchaser has not sufficient cash to pay a deposit and within the usual period take title, paying the balance. Possibly the purchase does not seem desirable on those terms. Yet he would be willing and able to pay the price in installments. In such events it is usual to have the financial clause provide for times and amounts of installments at stated intervals, and the payments to be applied first to interest on the purchase price, then to payment of charges such as taxes as they accrue, and finally towards payment of the unpaid balance of purchase price. Under such a contract it is usually agreed that the deed shall not be delivered until a certain amount has been paid upon the price. The usual custom is for the purchaser to give a purchase money mortgage for the balance of the price, the mortgage to be paid in such manner as may be agreed upon. For the seller's protection, the contract should also provide that in event of a default in payment by the purchaser, the contract be cancelled and all sums paid by the purchaser be deemed rent for the period from the time he took possession up to the default. (Appendix forms 12 and 13.)