Week-33

Writing/STEM Principles: 

Hello Homo Sapiens! Welcome back to Faces of Silicon Valley! This month, we’re continuing our exploration of places, ideas, and technologies that quietly shaped the world we live in today. From nanoscale science to towering coastal landmarks, these stories over the past TWO months continue to remind us that innovation often hides in plain sight.

Before we dive into this post, let’s check in with some updates!

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1) Monthly Publishing Reminder
Faces of Silicon Valley is currently operating on a monthly publishing schedule, allowing for deeper research and more thoughtful storytelling. This also means more time spent improving features like Gallery Glimpse and highlighting community voices.

2) Exploring Local History & Science
This month’s post blends local history with physics and engineering, a combination I’m hoping to explore more often. If you enjoy posts that connect places to scientific ideas, let me know—your feedback directly shapes future content!

3) Get Involved
Interested in being featured, sharing writing, or suggesting topics? Reach out through the Contact Us page or drop a comment below. Faces of Silicon Valley is built on curiosity and collaboration.

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Introduction to this week's post! 

Lighthouses are often admired for their beauty and symbolism, but behind their iconic silhouettes lies incredible engineering. This post focuses on Pigeon Point Lighthouse, one of California’s most recognizable coastal landmarks, and the remarkable science behind the Fresnel Lens, which is a technology that revolutionized maritime navigation and saved countless lives at sea.

Let’s take a closer look, shall we?! :) 

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Contrary to its name, Pigeon Point Lighthouse wasn’t named after the bird, but after a ship called Carrier Pigeon that wrecked nearby in 1853. The tragedy helped spur Congress to fund the construction of the lighthouse, which first lit its beacon on November 15, 1872. The towering 115‑foot brick tower once housed a first‑order Fresnel Lens which consisted of 1,008 hand‑polished glass prisms in 24 flash panels and was capable of producing over half‑a‑million candlepower. The lens rotated once every four minutes, creating a distinctive white flash every ten seconds, powered originally by a clockwork mechanism with a 45‑lb weight. Unfortunately, the lighthouse itself has been closed to the public since 2024 due to restoration processes. Despite that, visitors can still explore the Fog Signal Building, where the Fresnel Lens is beautifully displayed. 

A Fresnel Lens is made of concentric rings of cut glass instead of one thick, heavy piece. It’s helpful to think of a flattened, segmented convex lens. Each ring, or prism, is angled to bend and redirect the light from a central lamp so that all the rays emerge together in a tight, focused beam. This clever, stepped design enables the lens to be far thinner, lighter, and more efficient than traditional solid glass lenses. It captures light that would otherwise scatter and sends it out as a bright, powerful beam that can span over 20 miles. This is WAY better than the older systems which used mirrors or simple reflectors and typically lost up to 60–80% of light. With a Fresnel Lens, a minimum of 80% of the light is retained, making it much more effective at guiding ships at sea. 

The only problem was rotating these massive lenses, especially since some weighed several tons. The solution, proposed by Fresnel in 1825 and later refined in the late 19th century, was to float the lens assembly on a basin filled with mercury. Attached to the base of the lens was a donut-shaped ring that submerged into this mercury bath, creating an almost frictionless bearing. That meant a lighthouse keeper could rotate the enormous lens with just a light push which avoided heavy machinery. This low-friction system allowed reliable, consistent flash patterns (like Pigeon Point’s ten-second cycle), enabling mariners to identify different lighthouses.

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Comment Prompt! 

1. Had you ever visited or heard of Pigeon Point Lighthouse before reading this post?

2. What surprised you most about the Fresnel Lens or how it works?

3. Do you enjoy learning about the science behind historical landmarks? Why or why not?

4. Are there any local landmarks or historical sites you’d like to see featured in a future post?

Feel free to share your thoughts, questions, or ideas in the comments below. I’m excited to hear what stood out to you!

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Signing off, until next time!