Lighthouses had proved themselves essential almost as soon as navigation of the seas began. The earliest forerunners of the present-day structures probably were beacon fires kindled on headlands and capes to guide fishermen home and warn mariners off dangerous shores.

Frank Schubert, the country's last civilian lighthouse keeper, has seen it all - wild storms roaring in from the Atlantic; a fiery oil tanker collision; a baby whale on the rocks; courageous Coast Guard rescues. . . ."Some folks think the life of a lighthouse keeper's boring," says 72-year- old Schubert, shielding his eyes against the late afternoon sun that's painting Sea Gate in Brooklyn burnished gold.

"Well, I can honestly say I've never spent a boring minute on this job and I've been at it nearly three decades now. Never taken a vacation in all that time, either. No need for one. This place has everything a man could want. Smell that air! Look at that view! Understand how a place like this could grow on you?"

Understanding's easy. Schubert's immaculate little house, with its companion ivory tower (75 feet high), is a picture postcard in a picture postcard setting. Almost all the scenery on the western tip of New York's Coney Island where the lighthouse is located is spectacular - the rugged coastline; gulls swooping overhead; quaint Victorian buildings; tugs, freighters, even billionaire Donald Trump's new yacht passing by. And in the distance there's Old Orchard Light - the station where Schubert began his career so many years ago.

It was 1937. The computers and machinery that now are fast replacing the human element in lighthouse operation were just dreams. Few imagined the day would come when such technology would be able to guide sailors through the storm effectively; the day when automation would prove more economical and efficient than manpower.

Even fewer anticipated the closing of many lighthouses and would have been amazed to hear the arguments now being used: too expensive to run . . . not in a crucial spot . . . old fashioned . . . not really essential anymore.

Lighthouses, you see, had proved themselves essential almost as soon as navigation of the seas began. The earliest forerunners of the present-day structures probably were beacon fires kindled on headlands and capes to guide fishermen home and warn mariners off dangerous shores. The encyclopedia also tells of the ancient Libyans who built lighthouses to direct their sailors in the Mediterranean and hung metal baskets full of burning coal from poles on top of the towers.

Perhaps the most famous ancient lighthouse was the Pharos of Alexandria, built around 300 B.C., on an island near Alexandria in Egypt. Higher than the Statue of Liberty, its wood-fueled flames could be seen for 35 miles in clear weather. It was one of the wonders of the ancient world and served as a beacon for 15 centuries before it was finally toppled by an earthquake.

Given such a past, the future of the lighthouse must have seemed rock solid to Schubert when he began working as a buoy tender and later moved on to Old Orchard Light.

"Times were tough," he recalls, sitting in the warm, comfortable kitchen of the house where he and his late wife raised their family. "It was hard to find jobs and make enough money to live. Lighthouse work was steady and secure. Although the solitude was hard on some of the men - especially those at off-shore stations - it never bothered me much. There's something about the quiet - being away from all the hustle and bustle of the city - that helps a man to find out a lot about himself."

At Old Orchard, Schubert found out that hobbies could do wonders to fill the hours when chores were done. He took up a craft called marquetry and began creating scenes with inlaid pieces of wood. Today, the hobby's still a favorite, and pictures of ships formed by such woods as mahogany, maple and koa from the Philippines decorate the walls of his home. It's something he believes will take up the slack when the machines inevitably are installed and take over many of his duties.

"I want to stay on here and learn about the new equipment and how it ticks," he says. "I hope the Coast Guard will let me. Every time I think about moving and doing something else it just doesn't seem right. If this place is automated and then just left, vandals will have it ruined in a month. Now, you tell me, how can I let that happen after all these years? This is my home, my life."

Life at the Sea Gate Lighthouse, a landmark that dates from 1890, began for Schubert after his stint at Old Orchard and service at a lighthouse on Governor's Island. He learned how to carefully light the kerosene lantern (it required climbing the ladder to the lamp room of the tower each evening an hour before sundown and remembering to wear smoke-colored glasses to protect his eyes).

"If you forgot to put on those glasses, you went around half blind for days," he recalls.

His young sons often helped with chores; his wife was in charge of the log. It was a real family operation.

"We took a lot of pride in doing things up right," Schubert says. "Whenever the Coast Guard inspectors would come to look over the place they'd give us the highest ratings. Just look at this book, here. Their comments are recorded. Let me tell you, a place like this has to be in top condition and clean as a pin to get an inspector's OK. They're fussy. But, thank goodness, they're not on your back every minute. The Coast Guard gives you a lot of freedom and lets you run your own operation your own way and I like that."

Today, the lighthouse keeper still polishes, dusts and sweeps daily to keep everything looking shipshape. That's the way he likes to do things and it's something that hasn't changed a bit over the years. The kerosene lantern, however, has long since been replaced with electricity and it's no longer necessary for him to climb the skinny ladder every night just before sundown with the alcohol torch. These days a light sensor switch does the job.

Sure, it's easier, Schubert admits. But if a blackout occurred - an electrical outage - the Coney Island Light still would have to rely on the old kerosene lantern; he'd have to change the system back to cope with the emergency, since there's no auxiliary power to keep that beacon going.

True, there's less need these days for the beacon. Modern radio and navigational equipment has made many lighthouse services obsolete.

"I guess progress is what it's all about," he muses. "I mean, who would want to return to the whale oil lamps that were once used or the old-fashioned lenses and reflectors? I'm not against improvements. I just hate to see some of the old beauties boarded up, neglected and forgotten. Lighthouses are such importantparts of history, I don't like to see us lose any of them."

Lighthouses first came to the New World when lanterns were hung at harbor entrances. The first official structure was put up by the Massachusetts Bay Colony in 1716 on Little Brewster Island at the entrance to Boston Harbor. The building was blown up by the British in 1776, and there were only about a dozen similar buildings left in the colonies. But a little over a centrury later, 700 lighthouses to guide ships had been constructed along American coast lines and the banks of rivers.

The number grew until it reached about 1,400. The old Lighthouse Service was in charge at first, and many civilians and families were employed, especially at the on-shore stations. Then the U. S. Coast Guard took over and began replacing civilians with its highly trained professionals. Others left because they could find easier and better paying jobs elsewhere.

Schubert's the last civilian operator left. And the number of lighthouses has dwindled to 750. According to historian and writer Dennis Hanson in his article in Smithsonian Magazine, a mere 400 of these are still operational. The others have been decommissioned and closed. In some cases, American heritage societies have taken over and turned the old structures into maritime museums. Some private citizens and community groups also have given the aging lighthouses new leases on life by developing them into inns, restaurants and the like. But far too many, at least to the preservationists' way of thinking, have been destroyed, abandoned, lost to future generations.

The tragedy, preservationists point out, isn't just the historical waste. To lose a lighthouse also is to lose an architectural treasure.

Some say no two are alike - and the styles do vary greatly, running all the way from the Huge Cape Hattaras tower in North Carolina with its boldly painted stripes, to the square-shaped, bright red Holland Harbor Light in Michigan.

Although diversity is their hallmark, many lighthouses do feature the same basic New England design: a Cape Cod dwelling with the tower rising from the center or standing close by.

As for the signals that these towers send out - well, Schubert says they vary so that the captain of the ship will be able to accurately calibrate his position, mark his course and know just whose beacon he's seeing through the darkness or fog. The type of signal pattern and the colors each lighthouse sends out are recorded in the List of Lights. And no sailor worth his salt would leave home without it!

"At the Coney Island Light, we flash red every five seconds," the lighthouse opertor says. "They can see us about 16 miles out to sea. Keeping the light going is an important function, an important part of what I do here. But the job takes in many other things."

It's up to the lighthouse operator to be on the alert for emergencies and speedily contact the Coast Guard search and rescue teams for help. It's up to the operator to closely monitor weather conditions, to assist ships waiting for berths in New York Harbor, to keep the grounds well-tended and to be a jack-of-all-trades.

"When you're in charge of a light," explains Schubert, "you've got to be self-sufficient. You have to know how to be your own plumber, your own roof repairman, your own painter, your own carpenter - I built those kitchen cabinets over there and saved a bundle. I also think having good health and a rugged constitution helps. I have to climb the 87 steps that lead from the bottom of the tower to the lamp room at least once a day."

But the last civilian lighthouse operator in the country, the rugged keeper of the flame at the Coney Island Light, isn't the only one who has made it to the top. A group of senior citizens came visiting the other day, he says, and every one of them completed the climb. Around 400 visitors a year, in fact, make the pilgrimage to the picturesque residential community of Sea Gate just to see the lighthouse. And many of them talk the operator into letting them huff and puff up the ladder to the glass-enclosed area where the dazzling lamp waits for darkness.

Once there, most of them stand entranced - gazing out at the seascape. The wind gently rattles the windows. The world and its worries seem far, far away. The universal symbol for "safe journey, safe harbor" casts its spell.

"I don't know what it is exactly," the keeper of the Coney Island Light says, his face bathed in the bright red flame of the lamp. "But people of all ages and from all walks of life seem to get a kick out of coming up here. I've never run into anybody yet who didn't love lighthouses. And I do, too - even after so many years."