Philo McGiffin, a legendary midshipmen has been credited with a lot of legends, most untrue. Among them, standing on 3-2 of Bancroft Hall and shaking flour on the watch formation and rolling cannon balls down the steps of Memorial Hall into the Rotunda. Only one problem, Bancroft Hall did not exist when he was a midshipman. He died in the late 1800s. The Chapel was completed in the early 1900s. Therefore, I doubt if he had anything to do with placing a cover on the Chapel dome.
Uniform for watch was usually Service Dress Blue with or without sword belts. The announcement often got abbreviated to, assuming the SDB, "Uniform for watch standards is sword belts". The legend is that he showed up for watch formation wearing nothing but a sword belt.
Incidentially, he did accept a commission in the Chinese Navy and is considered the father of it.