“ The ironclad intruder will thus prove a severe monitor to those leaders . . . ‘Downing Street’ will hardly view with indifference this last ‘Yankee notion,’ this monitor.” It is also the name of an ironclad railway truck used for carrying a big gun. In America the raised part of the roof of a railway carriage or omnibus in which the lights or ventilators are placed is known as a monitor roof or top. In mining the word is applied to a jointed nozzle which may be turned in all directions, and is used in hydraulic mining. ”