At the present time thousands of lighthouses, light-ships, and light-buoys guide the navigator along the waterways and into harbors and warn him of dangerous shoals. Many wonderful feats of engineering are involved in their construction and in no field of artificial lighting has more ingenuity been displayed in devising powerful beams of light. Many of these beacons of safety are automatic in operation and require little attention. It has been said that nothing indicates the liberality, prosperity, or intelligence of a nation more clearly than the facilities which it affords for the safe approach of the mariner to its shores. Surely these marine lights are important factors in modern navigation. The first "lighthouses" were beacon-fires of burning wood maintained by priests for the benefit of the early commerce in the eastern part of the Mediterranean Sea. As early as the seventh century before Christ these beacon-fires were mentioned in writings. In the third century before the Christian era a tower said to be of a great height was built on a small island near Alexandria during the reign of Ptolemy II. The tower was named Pharos, which is the origin of the term "pharology" applied to the science of lighthouse construction. Caesar, who visited Alexandria two centuries later, described the Pharos as a "tower of great height, of wonderful construction." Fire was kept burning in it night and day and Pliny said of it, "During the night it appears as bright as a star, and during the day it is distinguished by the smoke." Apparently this tower served as a lighthouse for more than a thousand years. It was found in ruins in 1349. Throughout succeeding centuries many towers were built, but little attention was given to the development of light-sources and optical apparatus. The first lighthouse in the United States and perhaps on the Western continents was the Boston Light, which was completed in 1716. A few days after it was put into operation a news item in a Boston paper heralded the noteworthy event as follows: By virtue of an Act of Assembly made in the First Year of His Majesty's Reign, For Building and Maintaining a Light House upon the Great Brewster (called Beacon-Island) at the Entrance of the Harbour of Boston, in order to prevent the loss of the Lives and Estates of His Majesty's Subjects; the said Light House has been built; and on Fryday last the 14th Currant the Light was kindled, which will be very useful for all Vessels going out and coming in to the Harbour of Boston, or any other Harbours in the Massachusetts Bay, for which all Masters shall pay to the Receiver of Impost, one Penny per Ton Inwards, and another Penny Outwards, except Coasters, who are to pay Two Shillings each, at their clearance Out, And all Fishing Vessels, Wood Sloops, etc. Five Shillings each by the Year.