The battery of these vessels is surrounded by a breastwork six feet in height, plated with nine-inch armour. Entrance is gained to the turrets themselves from inside this breastwork. In the centre of the turret there are two cylinders, the one fitting over the other in a manner which keeps the whole steady even in rough weather. Small steam-engines placed inside the breastwork serve to turn the turrets, which, however, can also be worked by manual labour should necessity demand it. The ports present a striking contrast to those in the old wooden ships, by reason of their greatly diminished size. They just admit of the muzzle of the gun peeping through, and no more, being oval in shape, and about three feet in diameter lengthways. There can be little doubt that these small ports are an advantage, since they must afford greater protection to the gunners during action. When it is desired to alter the direction of the guns, the change is not effected by moving them in the ports, but by revolving the turret itself. Should it ever happen in action that the free movement of the turret should become impeded from some cause, then the only means of changing the direction of the guns would be to turn the whole ship. The turrets are armed with two twenty-five ton guns, carrying four hundred pound shot. The deck being flush, as has been mentioned, the guns can be fired straight ahead and astern, and command all sides. Less than one minute is needed to revolve the whole turret. This class of ships is believed to be able to keep up a constant steady fire whether in chase or in retreat. Abaft the funnel in these ships there is an upright oval tube rising some seventeen feet above the level of the main deck, plated with iron. The upper plate is pierced with several small horizontal slits, from which the tube has received the name of the "conning-house," for through these openings the captain can "con" or note whatever is going on outside, without himself being exposed to danger. This circular box just allows the captain to turn himself about in; and here must he stand in time of action, directing and governing the whole conduct of his ship by mechanical telegraphs. Of the many curious and remarkable features in these ships, one of the most remarkable is the extensive use made of machinery for every purpose. Engines revolve the turrets, raise the ashes from the engine-rooms, turn the capstans, work the rudders;--engines do everything. Three monitors similar to those just described were built for the defence of several of our colonies. The colony of Victoria, we believe, purchased their ironclad, the _Cerberus_, from the home Government; at any rate, the people maintain her at their own cost. Before the _Cerberus_ could make the voyage out to Melbourne, her sides had to be built up with thin iron plating for nearly her whole length. In the same way the _Cyclops_ and her companion-ships might be made fit to face any sea or weather.