The Light List shows the St. Augustine Lighthouse as exhibiting a flash every 30 seconds, the same as it is today. Stay tuned for the next installment in our lighthouse technology series, where we will discuss the kinds of lighting sources used to illuminate the St. Augustine Lighthouse over its history. Our Fresnel lens is still turning, sending its light 20 miles out to sea.
Come visit the lighthouse and see our historic lens at the top of the tower. Paul Zielinski is Director of Interpretation for the St. Lighthouse Technology: Clockwork Mechanism. Previous Next. It is like a traffic sign on the sea. Here are five other facts about lighthouses you should know. Top 5 Facts: Battle of Hastings. Visit Us. Who We Are. His statement follows:. 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 The sounds they gave out were generally low-pitched and very mournful?
Each one emitted a specific number of blasts every minute so it could be told apart from all others. Today, an automatic sensor, which detects moisture in the air, turns on the fog signals when needed.
There are also soundless fog signals called radio beacons an electronic device. These fog signals were not placed everywhere. Although some places experience no fog problems, fog-warning devices are very necessary m New England, on the Pacific Coast, and in Alaska.
In colonial times, before we became an independent nation, men realized the need for lighthouses at the major ports to help guide ships into the harbors, to prevent them from crashing, and thereby losing their precious cargoes.
So, the first lighthouses were built by the colonies which were called states after Most lighthouses were named for their location, but several were named after ships that wrecked themselves nearby before a lighthouse was built.
Before the days of electricity, they had to light the lamp at sunset and extinguish it put it out at sunrise. During an 8-hour watch at night they had to climb the stairs in the tower one to three times a night to check on the lamp and wind the weights.
Some lighthouses have as many as two hundred steps! The brass in the building had to be shined, and all the windows cleaned. Often it took a whole day to clean and polish the lens alone. It was very important to keep both the lens and the lantern room windows clean so the light would not be lessened in any way. A daily log had to be kept detailing everything from the weather to the amount of fuel consumed.
The Keeper also had to tend to the mechanism used to operate the fog signal. During the year many items had to be painted. The men and women of the Lighthouse Service were among the most dedicated civil servants, often performing in extreme hardship.
Keepers also saved lives. Ida Lewis rescued 18 people during her 39 years at the Lime Rock Lighthouse. Other keepers died on duty.
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