How Does a Lighthouse Work. You might also like More from author. Prev Next. Leave A Reply. Sign in. Welcome, Login to your account. Forget password? Remember me. Sign in Recover your password. The prisms do this by refracting or bending light and reflecting it as well. Refraction is the scientific word that is used to describe how light is bent as it enters or exits a dense transparent material or medium like glass at angle other than 90 degrees.
Reflection occurs when light bounces off the surface of smooth, shiny material like metal, glass, or water. Reflection can occur on both the interior and exterior surface of transparent object. The reflection of mountain range on the surface of a crystal clear alpine lake and the reflection of fish on the underside of the lakes surface are both great examples of external and internal reflection in action. This project won't present many difficulties; nevertheless, as I have not put it into execution, I won't require you to adopt it for your first lighthouse.
The mercury bath allowed the lens to operate in an almost frictionless environment and, additionally, allowed the speed of rotation to be dramatically increased.
Mercury float with section removed, showing the float attached to the bottom of the lens and basin attached to the pedestal. Mercury flotation was first used in Scotland in Later, Dr. John Hopkinson of Chance Brothers in England did further work to improve the mercury float design. High-speed rotation could not have been accomplished without the use of the mercury bath system, unless the driving clockwork was significantly increased in its power output, which would have been nearly impossible.
The mercury bath consisted of a donut shaped basin in which a relatively small amount of mercury was placed. Attached to the base of the lens was a large donut shaped ring that was submerged in, and supported by, the mercury, which was placed in the basin. This assembly provided a nearly friction less base for the lens to ride upon, allowing lenses weighing several tons to be started in motion with the push of a single finger. Mercury basins also had ball or roller bearings set in a track around the top of the central pivot shaft that kept the ring, attached to the lens, centered within the basin.
When the lens rotation was speeded by use of the mercury floatation system, lens panels could be reduced in number and increased in size, giving a much brighter flash.
The use of mercury as a replacement for chariot wheels or ball bearings posed a problem for the keepers who had to work with the liquid mercury. There was as much as pounds of mercury in the basin of a 1 st order lens.
Mercury poisoning can easily occur from the mercury itself or from the vapor, which is always present around the basin. Mercury can be absorbed through the skin or the vapor can be breathed in through the lungs.
In either case, mercury poisoning will cause permanent damage that is very difficult to diagnose. Often, mercury poisoning will cause severe mental problems. The keepers were required to keep the surface of the mercury clean and to ensure the mercury was maintained at the proper level by adding or removing the liquid mercury as needed. This brought the keepers into periodic contact with the mercury and its fumes.
A common practice, used to reduce the amount of fumes from the mercury, was to pour a layer of ordinary motor oil onto the surface of the mercury in the basin. A mercury float, including pedestal and clockwork case, was built and tested at the general lighthouse depot in Tompkinsville, New York for use in the Ashtabula Harbor Light Station, Ohio.
This was the first mercury float built in America and was installed in It was designed along lines similar to those then in use for large lenses, and was intended for the smaller sizes of illuminating apparatus. An individual lighthouse distinguished itself with its day mark -- the color schemes and patterns on the tower -- and its light signature.
For example, a lighthouse might emit two flashes every three seconds to distinguish it from a lighthouse that emits four flashes every three seconds. Even today, if the GPS goes on the fritz, crews reference light lists to plot a course -- those regional indices of lighthouses and their distinguishing traits. At points before their automation in the 20th century, lighthouses had to accommodate cumbersome systems as well as a light-keeping staff to keep shining 24 hours a day.
In addition to a lighthouse, a complete light station might include a fog signal building, a boathouse, living quarters for the keeper and his family and a separate oil house to cordon off the flammable agents that powered the lamps. No two lighthouses have been built the same. Early lighthouses used whatever materials were available locally: wood, brick, stone, concrete, reinforced steel and cast iron.
Some lighthouses are placed onshore overlooking the water, while some are built offshore on reefs or patches of rocks. Even the height of the tower changes from one lighthouse to the next depending on the view from the water. A lighthouse overlooking a foot There are regional similarities in construction, however: Lighthouses built in the Outer Banks of North Carolina are built in intervals so that if a ship maneuvering down the coast lost sight of one lighthouse, it would find the glow of the next one [source: Gales ].
Lighthouses have been around since ancient Egypt. And as maritime trade expanded, so did the presence of lighthouses around the world, from China to Indonesia to Africa to Estonia. Famously, the Stevensons, a Scottish family of lighthouse engineers that counted author Robert Louis Stevenson among its progeny, built 97 lighthouses along the Scottish coastline and elsewhere [source: Bathurst ].
Lighthouses first appeared in New England in In , Congress created the U. Lighthouse Establishment to bring lighthouses under federal control.
After first earning a second-rate reputation for the poor quality of its lighthouses, the United States became home to more than 1, lighthouses by [source: Ray]. And with more than lighthouses, the state of Michigan possesses more lighthouses than any other state [source: Michigan State Housing Development Authority]. Wood fires were the earliest illuminants. As lighthouses proliferated, lamps powered by coal, whale oil, kerosene and other fuels became commonplace. One of the most novel lighthouse inventions, the Fresnel lens, came along in and used a network of prisms to magnify a small amount of light and cast a beam over distances of 20 miles The lens was widely used across the pond, but under Stephen Pleasant, who oversaw lighthouses from to , U.
Soon after the establishment of the Lighthouse Board in , all lighthouses in the United States were equipped with Fresnel lenses.
In , the Statue of Liberty became the first lighthouse powered by electricity , and served as a lighthouse in New York Harbor for 15 years. Most lighthouses had gone electric by the s after access to electrical lines expanded.
0コメント