SECTION 1. Section one of Commonwealth Act Numbered Two hundred and twenty-three is amended to read as follows:
"SECTION 1. The Secretary of Public Works and Communications, with the approval of the President of the Philippines, is authorized to enter, from time to time, into contracts for the transportation of mails by air between any points within the Philippines for periods not to exceed five years. The base rate of pay in awarding such contract shall in no case exceed one peso per airplane mile for transporting a mail load not to exceed three hundred pounds. In fixing the base rate of pay, the passenger capacity of the planes carrying the mails should be taken into consideration. Payment for transportation shall be at the base rate fixed in the contract for the first three hundred pounds of mail, or fraction thereof, plus one-tenth of such base rate for each additional one hundred pounds of mail or fraction thereof, computed at the end of each calendar month on the basis of the average mail load carried by mile over the route during such months.