A few minutes later the mainsail was once more set; and no sooner was the tack boarded and the sheet dragged aft than we felt the difference, which was tremendous.  For whereas we had before been going along comfortably enough, despite the heavy rolling and pitching, the moment that she felt the extra pressure, due to the expansion of this large area of canvas to the gale, she lay down to it, until at every lee-roll the muzzles of the quarter-deck guns were buried in the boiling yeast that foamed and swirled giddily past to leeward, and sometimes surged in through the ports, filling the lee-scuppers knee-deep with water.  And whereas we had before ridden buoyantly over the head seas, with nothing worse than an occasional shower of spray flying in over the weather cathead, the frigate now plunged her bows savagely right into the very heart of them, quivering to her keel with the violence of the shock, raising a very hurricane of foam and spray about her figurehead, and shipping the green seas in tons over her forecastle at every dive, while the main tack groaned like a giant in torment as it seemed to strive to tear up the very deck of the ship.