Inspiring paintings, poems, songs, and numerous stories, lighthouses have become historical landmarks
over time because of their legendary history and their maritime importance.
Ever since man attempted travel by sea, navigational
tools & guides were used. In the very early days, mariners tended to sail
by day for visibility and near coasts. Natural landmarks, winds, ocean currents,
and the use of stars were the main aids available. Since electricity and the
light bulb were hundreds of years away, fires lit on shore were the earliest indications of nighttime seaside navigational. However, they were not very bright and needed to be tended frequently.
In 290 B.C., Colossus was erected at the entrance of
Rhodes which was built by Chares of Lindos. The sun-god of Helios was made of
bronze, measured 132 ft. high, and held a fire in his hand. 80 years later, it
was destroyed due to an earthquake. Later, Egypt constructed a lighthouse on
the island of Pharos. Measuring 425 ft. tall and built by Sostratos of Knidos
in 299-288 B.C., it marked the entrance of Alexandria. It too was destroyed because
of an earthquake. Also, the Romans were known to build at least 30 lighthouses
on the Mediterranean Sea.
The 1st beacons to be recorded in writing,
were built by the Greeks in the 6th & 5th century B.C. to mark the entrances of harbors, such as
Piraeus. A tower called the Torre de Hercules in Coruna, Spain has stood
since the 1st century A.D. and is actually still used today!
Lighthouses were not always used. Where water levels are too deep or where a lighthouse would be too expensive or impractical, lightships
were used. Not nearly used as much, they were still an effective landmark &
navigational option for seafarers.
Initially, unlit towers on land were used. It was raised in order to be visible at a distance. These
towers and their different styles were partly influenced by other uses such as a lookout, defense tower, or for residence. Soon after, small candles grouped together forming a larger “lamp”, were
put on tall posts, in nearby trees, or up onto a pole called “the swape”.
In Scandinavia, during the 1500’s, a fire was kept in an iron basket
which was raised & lowered to light and tend.
Before the 19th century, lighthouse towers
were built using wood or stone because the materials were readily available. Soon,
masonry towers were built because of their durability and were less vulnerable to fire.
Masonry towers were the most popular during the 1800’s. Around the
turning point of the 20th century, concrete towers reinforced with steel began to replace the brick masonry towers. The 1st was constructed in 1908 at Point Arena, California. Most major reinforced lighthouse towers are currently found on the west coast where they are best adapted
for the threat of earthquakes.
The illumination source of the lighthouse changed through time also. Early ancient
light towers were made of stone and used wood, charcoal, or tar. Wood burned
quickly and it needed to be tended to frequently. Charcoal or tar emitted fumes
& smoke which were hazardous. Whatever the source, it wasn’t very practical
and efficient. By the 1600’s, oil (whether animal or vegetable) lamps became
the primary choice. In 1765, Antonie Lavoisier developed a large spherical parabolic
beacon reflector. This allowed the rays of light from the tower to be focused. In 1782, Swiss physicist Aime Argand made a hollow wick increasing the air supply
which led to a virtually smokeless flame which was constant and 10x brighter. It
was called the Argand Lamp and it revolutionized tower lighting at that time. By
1855, Kerosene became prevalent and was used almost universally by 1889. In 1892,
acetylene (a pure chemical compound of Hydrogen & Carbon) was discovered. Using
acetylene was much cheaper and burned 20x brighter than kerosene.
In 1784, the catoptric optic was developed. It is a rotating reflector-lamp system driven by a clockwork weight mechanism in which it turned the reflectors
back & forth giving the impression of a light controlled by a light switch. In
1822, Augustin Fresnel revolutionized the lighthouse light. He began his optic
experiments in 1816 and by 1819, the French Academy of Sciences awarded him a prize for research on light diffraction. He manufactured, cut, & shaped individual pieces of glass together which acted
as several prisms which would refract & intensify the light to even greater power.
These lenses were used extensively throughout the world and known as Fresnel Lenses. Many of these lenses are being replaced today by other illuminating sources such as airport beacons or
plastic.
Today, all lighthouses either use electricity
or solar power for their source of light. 3 inventions or developments resulted
in the automation of today’s lighthouse:
1. Electricity
– Used in most lighthouses by 1940.
2. 1916 – Device
that automatically changed burned-out incandescent bulbs was developed.
3. Automated timing mechanisms to turn lights on & off, and the development
of electric fog signals.
As a result, most lighthouses do not need to
be manned. In the U.S. today, lighthouses exist in 31
out of 50 states.
