"When they (the Carthaginian traders) arrive, forthwith they unload their wares, and having disposed them in orderly fashion on the beach, leave them, and returning aboard their ships, raise a great smoke. The natives, when they see the smoke, came dawn to the shore, and laying out to view so much gold as they think the wares to be worth, withdraw to a distance. The Carthaginians upon this come ashore and look. If they think the gold enough, they take it up and go their way; but if it does not seem sufficient they go aboard their ships once more and wait patiently. Then the others approach and add to the gold till the Carthaginians are satisfied. Neither party deals unfairly with the other; for the Carthaginians never touch the gold till it comes up to the estimated value of their goods, nor do the natives ever carry off the goads till the gold has been taken away." In addition to the enormous profits of the carrying trade the Phoenicians had a practical monopoly of the famous "Tyrian dyes," which were in great demand throughout the known world. These dyes were obtained from two kinds of shellfish together with an alkali prepared from seaweed. Phoenicians were also pioneers in the art of making glass. It is not hard to understand, therefore, how Phoenicia grew so extraordinarily rich as to rouse the envy of neighboring rulers, and to maintain themselves the traders of Tyre and Sidon had to develop fighting fleets as well as trading fleets. Early in Egyptian history the distinction was made between the "round" ships of commerce and the "long" ships of war. The round ship, as the name suggests, was built for cargo capacity rather than for speed. It depended on sail, with the oars as auxiliaries. The long ship was designed for speed, depending on oars and using sail only as auxiliary. And while the round ship was of deep draft and rode to anchor, the shallow flat-bottomed long ships were drawn up on shore. The Phoenicians took the Egyptian and Cretan models and improved them. They lowered the bows of the fighting ships, added to the blunt ram a beak near the water's edge, and strung the shields of the fighting men along the bulwarks to protect the rowers. To increase the driving force and the speed, they added a second and then a third bank of oars, thus producing the "bireme" and the "trireme." These were the types they handed down to the Greeks, and in fact there was little advance made beyond the Phoenician war galley during all the subsequent centuries of the Age of the Oar.