Portland 的灯塔
http://en.wikipedia.org/wiki/Portland_Head_Light

Portland Head Light Station is a lighthouse located in Cape Elizabeth, Maine, USA. It has been called the "Most photographed lighthouse in
North America." The lighthouse is visited by nearly one million people per year.


History

Construction began in 1787 at the directive of George Washington, and was completed on January 10, 1791. Whale oil lamps were originally
used for illumination. In 1855 a fourth-order Fresnel lens was installed; that was replaced by a second-order Fresnel lens in 1864. That lens was
replaced with an autobeacon in 1958.


Portland Head Light in 1933In 1787, while Maine was still part of the colony of Massachusetts, George Washington engaged two masons from the
town of Portland, Jonathan Bryant and John Nichols, and instructed them to take charge of the construction of a lighthouse on Portland Head.
Washington reminded them that the colonial government was poor and that the materials used to build the lighthouse should be taken from the
fields and shores. They could be handled nicely when hauled by oxen on a drag, he said.

The old tower, built of rubblestone, still stands as one of the four colonial lighthouses that have never been rebuilt. Washington gave the masons
four years to build the tower. While it was under construction, the federal government was formed (in 1789) and it looked for a while as though the
lighthouse would not be finished. The first congress made an appropriation and authorized Alexander Hamilton, Secretary of the Treasury, to
inform the mechanics that they could go on with the completion of the tower. The tower was completed during the year 1790 and first lighted
January 10, 1791.

During the American Civil War, raids on shipping in and out of Portland Harbor became commonplace, and because of the necessity for ships at
sea to sight Portland Head Light as soon as possible, the tower was raised eight feet. When Halfway Rock Light was built, Portland Head Light
was considered less important and in 1833 the tower was shortened 20 feet and a weaker fourth-order Fresnel lens was added. The former height
and second-order Fresnel lens was restored in 1835 following mariners' complaints. The current keepers' house was built in 1891.

The station has changed little except for the rebuilding of the whistle house in 1975 due to it being badly damaged in a storm. Today, Portland
Head Light stands 80 feet above ground and 101 feet above water, its white conical tower being connected with a dwelling. The 200,000
candlepower, DCB 224 airport style aerobeacon is visible from 16 miles away. The grounds and keeper's house are owned by the town of Cape
Elizabeth, while the tower and fog signal are owned and maintained by the U.S. Coast Guard as a current aid to navigation.