If such company shall not agree as to the rate, time, speed, manner and terms of carrying the mails, the governor may appoint three commissioners who, or any two of whom, after a hearing on fifteen days’ notice in writing to the company of the time and place thereof, shall fix the price and terms. Such price shall not be less for carrying such mails in the regular passenger trains than the amount which the company would receive as freight on a like weight of merchandise transported in its merchandise trains, and a fair compensation for the post-office car.

If the postmaster general shall require the mail to be carried at other hours or a higher speed than the passenger trains are run the company shall furnish an extra train for the mail and be allowed an extra compensation therefor to be fixed as aforesaid.