This holiday celebrates the birthday of Samuel Plimsoll, a English politician and social reformer. He is best known for inventing the Plimsoll line, a line on a ship's hull indicating the maximum safe draft. The line revolutionized the safety of commercial sailing. Before this time, working on a commercial vessel was an incredibly dangerous job, as many shipping companies ignored safety standards. Now the Plimsoll Line is still an important part of insuring the safety of all kinds of ships.