Tag Archives: Fresnel Lens

The Lamp Changer

Did you know that the Lighthouse can change its own lightbulb? Well, it can and has been doing so for many years now. In 1936, electricity was first brought to the Lighthouse. This meant significant changes for the Lighthouse keepers since they no longer had to carry buckets of kerosene to the top of the lighthouse to burn in the lamp to create the light. Now light bulbs did the work of producing the light! But the keepers still had to stay up all night to make certain that the light bulb didn’t burn out, and that if it did, they were there to replace it.

Carlisle & Finch Lamp Changer in place in the Lighthouse lens room.

Years later, an innovative company in Cincinnati, Ohio came up with an answer to help make life easier for lighthouse keepers – a lamp changer for lighthouses! The Carlisle & Finch Company, the “Global Leader in Spotlight Technology,” specializes in the production of high quality optical products for a range of maritime uses, including within the United States Coast Guard and Navy.

Our lamp changer holds two, 1000-watt bulbs. The one in the center, or primary position (the large bulb on the left), is the operational bulb. The one to the right is in the backup position. If the primary bulb burns out, the electrical circuit is broken, releasing a switch. A spring at the base of the bulb’s housing piece then rotates the backup bulb to the primary position, where it snaps into place and completes the circuit. The backup bulb comes on automatically.

Here, I am holding the lamp (bulb) in the halfway position.

Did you notice that the bulbs look very different? The larger bulb is an historic 1000-watt GE bulb that is no longer made. The smaller bulb is the replacement that GE came out with a few years ago; it is also a 1000-watt bulb. The smaller bulb sits upon a ceramic block that serves two purposes: it dissipates heat so that the bulb lasts longer, and it places the filament at the same height as the older bulbs so that the focal plane of the light shines correctly through the lens. The old bulbs are so old (some dating to WWII) that we don’t know how long they will last, so we always put a new bulb in the backup position. If we used two old bulbs, they might both burn out on the same night, which as St. Augustine’s navigation beacon, would become a crisis situation. We only have a certain number of the old bulbs left, and once they are gone, it will be the end of an era. Our Lighthouse will then have two of the new bulbs in place, and thankfully, if the bulb changer ever wears out, the Carlisle & Finch Company is still in business to help us replace it.

Contributed by Director of Museum Services Rick Cain, edited by Student Intern Jayda Barnes

Enlightened: Episode 1, Part 3

Join us in this edition of Enlightened! as we continue our look into the history and science behind the Fresnel lens. In this installment, we will talk a little more about French scientist Augustin Fresnel and how his incredible invention shaped lighthouses forever!

Make sure you subscribe to our YouTube channel for future episodes of Enlightened!, a Nation’s Oldest Port educational program. 

Enlightened: Episode 1, Part 2

Did you know the U.S. Lighthouse Service initially declined the use of Fresnel lenses?

In part two of our first episode of Enlightened! (click here if you haven’t seen it yet!), find out why the federal government refused to utilize these revolutionary new lenses even after they were adopted throughout much of Europe.

Enlightened! is a St. Augustine Lighthouse educational program designed to serve our mission to discover, preserve, present and keep alive the stories of our Nation’s Oldest Port as symbolized by our working St. Augustine Lighthouse.

Are you ready to get “Enlightened”?

Presenting Enlightened! A New St. Augustine Lighthouse Educational Program

Have you ever wondered about the history and science behind the St. Augustine Lighthouse? Well, wonder no more! We are going to take you along on an exploration of all the amazing things we do here at the St. Augustine Lighthouse & Maritime Museum in our new YouTube series, Enlightened!

Enlightened is a way for us to share more with you — more stories, more history, more preservation, and more of the research we are doing every day to expand our understanding of people who interacted with the waterways around St. Augustine as part of their livelihood.

As the series grows and expands, we hope to add more interviews, viewer Q&As, and other elements that will allow our viewers to interact with the show and get all their burning Lighthouse questions answered.

Episode 1: The Fresnel Lens

For our first episode, we wanted to explore the heart of our Lighthouse (and all lighthouses, for that matter): the Fresnel lens! This magnificent piece is equal parts science and art, built with care and now preserved with care by our Museum staff.

Join us as we go inside the lens room (one of the few places at our Museum that is not accessible to the public) for an up-close look at our first order Fresnel lens.

Make sure you subscribe to our YouTube channel to catch each additional installment of the Fresnel lens episode in the coming weeks.

And don’t forget to follow us on FacebookInstagram, and Twitter for more great content!

Paul Zielinski is Director of Interpretation for the St. Augustine Lighthouse & Maritime Museum. He received his master’s degree in Public History from the University of West Florida and joined the lighthouse family in 2011.

Lighthouse Technology: Clockwork Mechanism

This next installment in our series on lighthouse technology focuses on the clockwork mechanisms that rotate Fresnel lens, giving lighthouses their distinctive flashing patterns.

Click the link below to read previous post in the series:

Light Characteristic

Lighthouses are equipped with unique light characteristic or flashing pattern that sailors can use to identify specific lighthouses during the night. Lighthouses can achieve distinctive light characteristics a few different ways. A lighthouse can flash, which is when brief periods of light interrupt longer moments of darkness. The light can occult, which is when brief periods of darkness interrupt longer moments of light. The light can be fixed, which is when the light never goes dark. A lighthouse can use a combination of flashing, occulting, or being fixed in a variety of combinations and intervals to create an individual light characteristics. Continue reading