All persons shall be received into such ferryboat or other vessels, as aforesaid, and conveyed across the water course over which the same shall be established, according to their arrival or first coming to the said ferry: Provided, that all public officers, or such as go on public or urgent occasion, as post riders, couriers, physicians, surgeons and midwives, shall, in all cases, be the first carried over, where all cannot go at the same time.