About ninety per cent. of the batteries of the eight larger vessels were divided, as is usual, between the two sides of the ship, so that only one half of the guns could be used at any one time, except in the rare event of having an enemy on each side; and even then the number of the crew is based on the expectation of fighting only one broadside. A few guns, however, varying in number in different ships, were mounted on pivots so that they could be fought on either side. In estimating the number of available guns in a fleet of sea-going steamers of that day, it may be roughly said that sixty per cent. could be brought into action on one side. In the Mississippi Squadron sometimes only one-fourth could be used. To professional readers it may seem unnecessary to enter on such familiar and obvious details; but a military man, in making his estimate, has fallen into the curious blunder of making a fleet fire every gun, bow, stern, and both broadsides, into one fort, a hundred yards square; a feat which only could be performed by landing a ship in the centre of the works, in which case it could enjoy an all-round fire. The nine gunboats carried one heavy and one light gun, both pivots and capable of being fought on either side. None of this fleet could fire right ahead. All the vessels were built for ships of war, with the exception of the Varuna, which was bought from the merchant service.[2] The mortar-schooners each carried one XIII-inch mortar. Of the six gunboats attached to this part of the expedition, one, the Owasco, was of the same class as the Cayuga and others. The Clifton, Jackson, and Westfield were large side-wheel ferry boats, of the ordinary double-ended type; carrying, however, heavy guns. They were powerful as tugboats and easily managed; whereas the Miami, also a double-ender, but built for the Government, was like most of her kind, hard to steer or manoeuvre, especially in a narrow stream and tideway. The sixth was the Harriet Lane, a side-wheel steamer of 600 tons, which had been transferred from the Revenue Service. The tonnage and batteries of these steamers were:[3]