Even of fifteen and sixteen rows of oars, in the navy of Demetrius Poliorcetes. These were for real use: the forty rows of Ptolemy Philadelphus were applied to a floating palace, whose tonnage, according to Dr. Arbuthnot (Tables of Ancient Coins, etc., p. 231 - 236), is compared as 4½ to 1 with an English 100 gun ship.