Locktenders on the C&O Canal were responsible at all hours, by night as well as by day, for passing all boats and floats that came to their locks. Each time a boat passed through a lock, a boat captain depended on the locktender’s skill, because the wooden lock gates had to be light enough for one man to move yet strong enough to hold back 140,000 gallons of water. A skilled locktender judged and adjusted the flow of water into or out of the lock to reduce danger to both boat and lock, while also maintaining the liftlocks themselves, since neglect or carelessness could bring disaster. In return for a small monthly salary, an acre of land, and a house, locktenders answered the horn blast of boatmen even at 2 a.m. or on Sunday, because time was money. Lift locks raised and lowered boats to overcome changes in elevation: a downstream boat entered the lock, the mules were unhitched, the upstream gates were closed, the downstream paddles were opened so water flowed out and lowered the boat, and once the water levels were equal, the downstream gates were opened, the mules were hitched again, and the boat moved on.