SECTION 1. Section twelve hundred and thirty-nine of the Administrative Code is hereby amended by adding, at the end thereof, the following paragraph, to be known as sub- section (f) :
"(f) A certificate of the Bureau of Posts to the effect that it received timely notice of the sailing of the vessel: Provided, That the Collector of Customs shall not permit any vessel to sail for a foreign port if the master or agent thereof refuses to receive bags of mail delivered to the same by the Bureau of Posts for transportation for a reasonable compensation. In case the Director of Posts and said master or agent do not come to an agreement concerning the amount of the compensation to be paid for the carriage of the mail, the matter shall be submitted for decision to a board of referees composed of three members, appointed, respectively, by the Bureau of Posts, the agency of the company to which the vessel concerned belongs, and the Bureau of Customs, which board shall fix a reasonable rate of compensation."