Fresnel Lens Yesterday and Today

With the long, dark winter nights we’re experiencing in the Northern Hemisphere, it is a good time to celebrate the marvel of an invention that brought light to our world centuries ago, and still today.

Fresnel Lens, 5th Order, Angel Isl., CA

Even before the first light bulb was invented, a powerful lens was invented.

It was a modern invention of the 1820s that revolutionized the sciences of light and marine navigation.

The lens design, created by a physicist, was maximized to capture light reflection and refraction. It is an array of prisms managing the mechanics of light, extending the light to then-unprecedented lengths.

Fresnel Lens Mechanics

The inventor, Augustin Fresnel (1788-1827), lived on the rugged west coast of France near Brittany, where tragic shipwrecks repeatedly occurred and human lives frequently perished. He invented the lens for lighthouses, to light up the coast more efficiently for ship captains to see what was in front of them. The first Fresnel lens was installed there, on the coast of France, in 1822.

A Fresnel lens could easily throw its light 20 or more miles.

France, and then Scotland, commissioned the lenses for lighthouses; eventually they spread across the world. The Fresnel lens came to U.S. lighthouses in the 1850s.

Fresnel Lens, 5th Order, Vashon Isl., WA

Prior to the Fresnel (pronounced fray-NEL) lens invention, oil lamps supplied the light and various inventions helped extend the light, but it was not enough to prevent shipwrecks.

I came upon this discovery not by navigating a ship along the coast, but by hiking on an island in the San Francisco Bay. Angel Island.

Angel Isl., SF Bay, CA

In the visitor center, a nearly two-foot glass structure shaped like a beehive was perched on a stand near the door–caught my attention.

Angel Isl. Visitors Ctr, CA

I am one of those people who stops in their tracks for shadows and sunbeams, fascinated by reflections and refractions. And this giant piece of glass was winking up a storm at me.

It is 21.3 inches high (.54 m). Fresnel lenses come in different sizes, or orders. Both lenses in this post are 5th Order. 1st Order is the largest, 6th Order is smaller. Link for more info is below.

Fresnel display, Angel Isl., CA

Fresnel lens base, Angel Isl., CA

The original Fresnel lenses can often be seen in lighthouses, like this one at Point Robinson on Vashon Island in Washington. The lamp/lens is inside the lighthouse (below), visible underneath the red, cone-shaped roof.

Vashon Island, WA Lighthouse. Photo: Athena Alexander

Here is a closer look at the lens, with majestic Mount Rainier presiding in the background.

Fresnel Lens, Vashon Isl., WA

Though there are still Fresnel lenses in lighthouses today, the science has largely been replaced by navigational systems like radar and radio signal towers and global positioning systems (GPS).

There are many lighthouses that still have the original Fresnel lenses, most of which are no longer operational. Almost always the lens/lamp is there due to a concerted effort by maritime enthusiasts, volunteers, and donations. Today they are highly regarded and valuable treasures.

The United States Lighthouse Society has a website filled with information about U.S. lighthouses including two lists of lighthouses that have operational and non-operational Fresnel Lenses.

Link: Fresnel Lenses in the U.S.

Link: Operational Fresnel Lenses in the U.S.

Link: Wikipedia Fresnel Lens

Link: Augustin-Jean Fresnel Wikipedia

The magic of the Fresnel lens does not stop in the 1800s. Today working Fresnel lenses are found in spotlights, floodlights, railroad and traffic signals, emergency vehicle lights and more.

Photographers use them to illuminate a scene. Athena uses a Fresnel lens flash extender on her camera, especially when we are out birding on night walks or dark days. It is a flimsy plastic lens that attaches to the flash unit and extends the flash up to 300 feet (91 m).

She captured this scene below with her “Better Beamer” flash extender. We were in the Belizean rainforest when a spectacled owl had just snatched up a fer-de-lance snake and landed in a tree 200 feet away (61 m).

Spectacled Owl with Fer-de-lance snake, Belize

The Fresnel lens has been bringing light into this world for ages, whether it was preventing fatal shipwrecks two centuries ago or capturing dynamic owl scenes today. That is something to celebrate.

Written by Jet Eliot.

Photos by Athena Alexander.

Athena with Better Beamer on camera

My Favorite River

Elephants in Chobe River

Our California winter this year has been blessed with abundant rain. As I walked in my neighborhood park last week, I marveled at the numerous rivers and streams.

 

I pondered what my favorite river on earth was, thought about it all week.

 

Rivers traverse all the continents. Over the centuries, cities have been founded on rivers for their power. They support large populations, and carry heavy loads of people and products. Rivers are the basis for the growth of civilization.

 

I have known so many rivers. How could I pick just one? Could you?

 

One favorite at the top of my thoughts: the Chobe River in Botswana. A popular watering place for African game. We watched wild dogs celebrating a kill, elephants crossing, and hundreds of ungulates.

Wild Dogs, Chobe River Nat’l Park, Botswana

 

Chobe River, zebra crossing from Botswana into Namibia

 

Waterbuck, Chobe River, Botswana, Africa

 

Then there is the Zambezi, another favorite. It is immense, and one of its most spectacular features: Victoria Falls.

 

Victoria Falls, Africa

Zambezi River

Zambezi sunset

In Zambia, where the Chobe and Zambezi Rivers converge, we had many lively experiences as we waited for the ferry to cross the river.

Waiting for the ferry at the Zambezi River, Zambia

Zambezi River crossing, Kazungula Ferry

 

And the Luangwa River, a major tributary of the Zambezi, holds the largest concentration of hippos in the world. Native residents share the river with crocodiles and hippos.

 

Hippos and Fishermen, Luangwa River, Zambia

 

 

Folks who fish rivers can read the water like a book.

 

Across the world in South America is the Amazon; we spent a week on the Madre de Dios River, a tributary.

 

It was buggy and humid in Amazonia, almost uninhabitable. I treasured the time we spent cruising this river, for the cool breeze and mosquito relief; and the myriad of wildlife species.

Boarding the boats, Manu, Madre de Dios River

 

Amazon river (near top) and jungle, aerial photo

Red and Green Macaws extracting nutrients from the river wall (photo by B. Page)

I have many favorite rivers elsewhere, too. My home country has so many rich riverways. The Yellowstone River, a tributary of the Missouri, brings frigid waters tumbling down from the Rocky Mountains.

Yellowstone Falls

The Colorado River, the Snake, the Columbia…and many more that I have had the opportunity to behold.

Colorado River, CO

In California, my home state, the Sierra Mountains deliver our highly revered water every day. We talk in winter about the snowpack, and every time officials measure the snow levels it makes all the newspapers, because this is the year’s source of survival. Dozens of rivers transport this liquid gold to us.

Deer Creek, CA; in the Sierra Nevada mountains

Drought and fires haunt us, and we revel when it rains.

 

What about the river of my childhood, the Mississippi? I was born and raised in the Midwest, where the Mississippi is integral. I’ve had decades of adventures on this river’s numerous branches.

 

Horicon Marsh sunset, Wisconsin

 

Could the Mississippi be my favorite?

Mississippi River basin. Courtesy Wikipedia.

As I continued to ponder the earth’s rivers, I remembered my times on the Rhine, the Danube, the Thames, the Amstel, and more.

Amsterdam bridge

 

Australian rivers, where I saw the rare Papuan Frogmouth (bird) from a motorboat; and my first wild platypus.

Papuan Frogmouth, Daintree River, Australia

Platypus

As I walked in the park beneath the California oak trees, I heard rambunctious acorn woodpeckers conversing, and red-tailed hawks declaring their territories.

 

I love it that every day the river here is different depending on the light, time of day, precipitation.

 

It is here that I finally got the answer I was seeking. For today, my favorite river is this one…

 

…where my feet are planted, where my eyes take in the ever-glinting movement, and my spirit is calmed by the whispering waters.

Northern California neighborhood park

This funny little river, a stream, really. Quiet, perhaps unnoticed by some, it is a wealth of life and bliss.

 

Written by Jet Eliot.

Photos by Athena Alexander unless otherwise indicated.

Male Kudu, Chobe River, Botswana, Africa

 

Caribou of Denali National Park

Caribou, Denali NP, Alaska

The great state of Alaska boasts a healthy population of caribou. During a visit to Denali National Park in central Alaska, we saw caribou several times.

 

A large ruminant mammal in the deer family, Rangifer tarandus are the North American species; they occupy a substantial range in Alaska and Canada (see maps below).

 

Denali NP, Alaska

Equipped with large antlers for shoveling snow and specialized nasal passages that warm incoming frigid air, this mammal lives in the coldest areas of North America.

 

Upon first setting eyes on the caribou, it is the antlers that command your attention–an impressive rack. The caribou shed the rack very year, so the Denali Visitor Center had discarded racks out for viewing; they were so heavy I could barely pick up one by myself.

 

In this species, unlike all the other mammals in the deer family, both genders grow antlers.

 

Other interesting facts about the Denali caribou:

• Their color varies, the coat changing with the seasons
• Their coat consists of two layers, for thorough insulation
• Size: 4′ tall at shoulder (1.22 m); 8′ in length (2.5 m)
• Weight: Bulls 350-400 lbs (159-182 kg); Cows 175-225 lbs (80-120 kg)
• They migrate in large herds, usually through adverse conditions

 

Denali NP

 

Denali herd info here

and

Wikipedia overview here. 

 

We occasionally came upon them while hiking, and although their size is intimidating, the caribou are gentle animals. We let them graze, and they let us marvel at their beauty and strength.

 

Some caribou subspecies have gone extinct or are diminishing for various reasons. In America, for example, it is very rare to see a caribou unless you go to Alaska.

 

According to Alaska’s Department of Fish and Game, there are 32 herds in Alaska/Canada, estimating 950,000 individuals.

 

In Denali National Park, the 2013 census count recorded 2,230 caribou. In the park they are, in general, protected.

 

Other parts of Alaska, however, allow regulated hunting and harvesting of caribou.

Denali Alaska

While caribou live in many parts of the world, we call them different names depending on where one lives. In the U.S., this mammal is called a caribou; unless they are domesticated, in which case they are called reindeer. In Europe, caribou are called reindeer.

 

Whatever you call them, they are a strikingly beautiful mammal with a hardy lifestyle and elegant antlers.

 

Photo credit: Athena Alexander

North America Caribou Range Map, courtesy Feldhamer, Thompson, Chapman; Wild Mammals of North America

 

World Caribou/Reindeer Range Map, Courtesy Wikipedia

 

Kingfishers of the World

Azure Kingfisher, Australia

A bird widely distributed across the world today, the kingfisher inhabits almost every continent (map below). This successful and thriving species has fossils that date back 30-40 million years.

Forest Kingfisher, Australia

 

Contrary to their name, not all kingfishers catch and eat fish; some species prefer frogs, snakes, worms, and more. Wikipedia overview.

 

Green Kingfisher (female), Belize

 

Though sources differ, there are approximately 100 species of kingfishers. Largely tropical birds, the majority inhabit the Old World tropics and Australasia.

 

The species we see most in North America is the belted kingfisher,.   In Europe, the kingfisher most commonly seen is appropriately called: common kingfisher. There are 10 species in Australia, 18 in Africa.

 

Whenever I am walking around a lake or river and hear the characteristic ratcheting of the belted kingfisher, whatever I am doing, I look up and search for this avian friend.

 

Australia, Kakadu Nat’l. Park

Kingfishers have a disproportionately large head and long, pointy bill; with short legs and stubby tails. They range in size from 3.9 inches long (10 cm) (African dwarf kingfisher) to 18 inches (45 cm) (giant kingfisher).

 

Giant Kingfisher, Botswana

When you come across a kingfisher, they are often perched on a branch, scanning the ground or water below. One of the easier birds to spot, they have bright colors, a distinct shape, and a predictable behavior.

 

Kingfishers have excellent vision, including binocular and color; and are able to recognize water reflection and depth. Some species have eye membranes for water protection. The pied kingfisher, for example, has a bony plate that slides across the eye on water impact.

 

Pied Kingfisher, Botswana

 

Blue-winged Kookaburra with frog in mouth, Australia

 

Little Kingfisher, Australia

Once the kingfisher spots the prey, they swoop down and snatch it, return to the perch. Holding the prey in their strong bill, they beat it against the limb, breaking it down to a sizeable portion for consumption.

 

Sometimes kingfishers will hover above water and dive in for fish.

Green Kingfisher (male), Belize

 

A kingfisher discussion would not be complete without mentioning the laughing kookaburra. Although this kingfisher lives primarily in Australia, many of us all over the world have heard of it, from the song. “Kookaburra sits in the old gum tree….”

 

Laughing Kookaburra, Australia

You can hear the great old children’s song, written by an Australian music teacher in 1934, here: the song

 

The real-life sound of a laughing kookaburra is truly wonderful. When I first heard it in a park in Sydney, it startled me.

 

Loud and cackling, it sounds nothing like laughter. You might think it was a monkey (or a wild beast) if you didn’t know better. Kookaburra call. 

Brown-hooded Kingfisher, Zambia

With a variety of specialized hunting skills, successful worldly range, and striking  colors, this bird is one that many of us have been celebrating our whole life.

 

Photo credit: Athena Alexander

Kingfisher range. Courtesy Wikipedia.

 

 

 

 

 

Our Migrating Ducks

Cinnamon Teal, Sacramento National Wildlife Refuge, Calif. Male in front, female in back.

Fall and spring bird migrations are exciting natural phenomenon that occur every year in all parts of the world, as it has been for millenium. Additionally, amid milder climates of the Central Valley in California, the migrating birds reside here in agricultural fields and refuge ponds for the winter.

 

American Wigeon, male

From November through January there are hundreds of thousands of wintering birds here that we don’t see at other times of the year, especially ducks and geese, but also cranes and other bird varieties. The migratory route in California is called the Pacific Flyway, and the birds travel here from numerous northern locations.

 

Northern Pintail, Colusa Nat’l. Wildlife Refuge, Calif.

Photographed here are a few of the ducks that we are lucky to have visit for the winter. By mid-February they will almost all be gone.

 

Buffleheads, SNWR; male, left; female, right

Ducks such as mallards and coots are here year-round, so they are not pictured here.

 

There are four migratory routes in North America and additional migratory routes in the eastern hemisphere. See maps below.

Pintails, Sacramento NWR

More info:

Pacific Flyway

North American migration routes

General Bird Migration

 

When they arrive and when they depart varies every year, depending on many factors, especially climate. The bird species also vary from year to year. Sometimes there are larger populations than other years, depending on how successful and/or brutal the year has been.

 

Northern Shoveler, California

Like anything in nature, there are a large amount of variables and nothing is predictable. For me, that’s the true joy of nature.

 

Photo credit: Athena Alexander

 

World Bird Migration Flyways. Courtesy WysInfo.com

 

U.S. Waterfowl Flyways. Courtesy Wikipedia.

 

Amsterdam

Amsterdam houses

As the capital and most populated city in the Netherlands, Amsterdam is a spirited and unique city.

 

It is popular among tourists for many attractions:  museums, canals, the Anne Frank house, the red-light district, tulips, and cannabis coffee shops, to name a few.

 

This is a city of deep history, starting as a fishing village in the late 12th century, developing into one of the world’s most important ports in the 17th century, the Dutch Golden Age.  Today the region is a modern metropolitan center and cultural capital with a population of approximately 2.5 million.  Click here for more info.

 

Rijksmuseum facade, Amsterdam. Courtesy Wikipedia.

There are so many museums it was impossible to see them all in one week. We visited the city’s two most famous museums:  Rijksmuseum and Van Gogh Museum.

 

Other notable museums include:  Stedelijk Museum, the Hermitage Amsterdam, and Amsterdam Museum.

 

The Milkmaid by Johannes Vermeer (c. 1657-58). Courtesy Wikipedia.

The Rijksmuseum is an art and history museum, with an extensive collection of Dutch masters.  There are over 2,000 paintings from the Golden Dutch age celebrating Rembrandt, Vermeer, Hals, and many more masters.  More about Rijksmuseum here.

 

There is also an incredible art exhibit, including Dutch masterpieces, in the Amsterdam Schiphol Airport.  It’s free.

 

Van Gogh Museum, Amsterdam. Courtesy Wikipedia

The Van Gogh Museum, located near the Rijksmuseum, is the largest Van Gogh collection in the world (pronounced “Van Goff” by locals).

 

This was an incredible collection featuring the paintings, drawings, and letters of the famous former Amsterdam resident.  More info here.

 

Amsterdam bridge

My favorite part:  the waterways.  The canals were built in the early 17th century as an urban planning project.

 

In addition to the Amstel River, Amsterdam has three main canals that form a concentric circle around the city, from which many other canals stem.

 

The canal ring area is designated a UNESCO World Heritage site.  There are 60 miles (100 km) of canals, 90 islands, and 1,500 bridges.  Canal boat tours are readily available and affordable.

Aerial photograph of Amsterdam canals. Courtesy Wikipedia.

Tulips abound at Keukenhof Gardens, less than an hour away from Amsterdam in the town of Lisse.  It is open for eight weeks from March to May, highlighting seven million tulip bulbs.

 

Amsterdam boat (Athena’s waving in background center)

Navigating through the city on boat or bicycle, visiting some of the richest art museums in the world, and enjoying the many elegant sites of Amsterdam is a true pleasure.

 

 

Photo credit:  Athena Alexander (unless otherwise noted)

Ring-necked Pheasant

Pheasant, California

Phasianus colchicus, also known as the common pheasant, is native to Asia, and was introduced in North America in the 1880s.

 

Due to their adaptability to many climates, and ability to breed in captivity, this well-known and widespread game bird can now be found across the globe. Between hybridization and captive breeding, there are about 30 subspecies.

 

Ring-necked pheasant, Mongolian subspecies; courtesy Wikipedia

The basis for this bird’s successful proliferation is its game bird status.   Since stone age times, and the Roman Empire too, this bird has been a popular game bird for hunters, for sport and food, then and now.

 

As a birder, I can never get enough of this exotic bird, and search earnestly for their presence when birding in marshes.  The showy male has a white neck ring and numerous colors, spotted patterns, a bright red wattle, and a long, streaked tail.  Gold, brown, green, purple, white, and red adorn the male; while the female has gold and brown with elaborately patterned markings.

 

They forage in fields on grain and seeds, and have an expansive diet including fruit, berries, invertebrates, and small vertebrates.  More pheasant info here.

 

Courtesy Wikipedia

In spite of their kaleidoscopic  colors, pheasant are skillful at hiding in the tall grass.  It is common to hear their call and lifting wings as they move further out of photographic range.  Click here for what we hear.

 

I also get a thrill out of hearing their cackling call on television shows.  It is frequently used as a general wildlife background sound byte in fictional British mysteries and other movies.  Sound engineers use it to evoke a frightening, mysterious presence.

 

Whether I am birding in the marshes, or watching British mysteries, two much-enjoyed activities, I am delightfully hosted by this elegant bird.

 

Photo credit:  Athena Alexander unless noted otherwise

A Toast to The Queen

Fairmont Empress Hotel, Victoria, Canada

Queen Elizabeth II:  United Kingdom’s longest serving monarch, surpassing Queen Victoria on Sept. 9, 2015.

 

Her reign of over 63 years and 7 months expands 13 UK prime ministers and 12 US presidents.  She became Queen on February 6, 1952 at the age of 25 .

 

Photo credit:  Athena Alexander

Queen Elizabeth II