"5.01 All payments due under this contract shall be made in dollars.
"5.02 Unless otherwise agreed between the parties the contract price shall be paid by the purchaser to the seller in four (4) instalments in the manner set out below:
"5.03 The payment of all such instalments shall be effected by cable transfer to the seller's bank.
"5.04 If the purchaser fails to make any payment required in clause 5.02 above the purchaser shall, subject to clause 14.02, pay interest at the rate of ten (10) per cent. per annum on the unpaid amount of such payment from the date when due up to and including the date of actual payment.
"5.05 (1) If the purchaser defaults in the payment of any amount due to the seller under sub-clauses ( b ) or ( c ) or ( d ) of clause 5.02 for twenty-one (21) days after the date when such payment has fallen due the seller shall be entitled to rescind the contract.