Read it through once

Imagine the benefits of so admirable a system in a piece of river twelve or thirteen hundred miles long, whose channel was shifting every day! The pilot who had formerly been obliged to put up with seeing a shoal place once or possibly twice a month, had a hundred sharp eyes to watch it for him, now, and bushels of intelligent brains to tell him how to run it. His information about it was seldom twenty-four hours old. If the reports in the last box chanced to leave any misgivings on his mind concerning a treacherous crossing, he had his remedy; he blew his steam-whistle in a peculiar way as soon as he saw a boat approaching; the signal was answered in a peculiar way if that boat's pilots were association men; and then the two steamers ranged alongside and all uncertainties were swept away by fresh information furnished to the inquirer by word of mouth and in minute detail.