For night sailing the arts of astronomy and computation had to be studied;[1428] the aspect of the heavens at different seasons had to be known; and among the shifting constellations some fixed point had to be found by which it would be safe to steer.

The last star in the tail of the Little Bear--the polar star of our own navigation books--was fixed upon by the Phoenicians, probably by the Sidonians, for this purpose,[1429] and was practically employed as the best index of the true north from a remote period.

The rate of a ship's speed was, somehow or other, estimated; and though it was long before charts were made, or the set of currents taken into account, yet voyages were for the most part accomplished with very tolerable accuracy and safety.

An ample commerce grew up under Sidonian auspices.

After the vernal equinox was over a fleet of white-winged ships sped forth from the many harbours of the Syrian coast, well laden with a variety of wares--Phoenician, Assyrian, Egyptian[1430]--and made for the coasts and islands of the Levant, the AEgean, the Propontis, the Adriatic, the mid-Mediterranean, where they exchanged the cargoes which they had brought with them for the best products of the lands whereto they had come.