House in the sky nestles on a Vermont mountaintop

It was a long, steep climb up the mountain -- hundreds of feet, in fact -- after inching the old Volkswagen beetle as far as the makeshift gravel road would take us.

Then, hoping out of the car, Michael and Gerlinda Marti, their 12-year- old son, Chris, my college-age daughter, Janet, and I trudged the rest of the way on foot. Once on top, it was easy to understand why Mike Marti, an aeronautical engineer, and his German- born wife had spent hundreds of fingernail-breaking hours over seven years, plus a lot of money, to build their "observatory in the sky."

"Come over and see this view," Mike calls as we walk around the outside deck of the eight-sided house.

"Some people say you can see Mt. Washington, but you really can't," he adds. New England's highest peak is 150 miles to the east. However, on the other side of the deck you can indeed bask in a magnificent view of the Green Mountains of Vermont.

There's no one else around, just the animals and birds.

Why build a small retreat on the dome of a 3,000-foot mountain that is totally inaccessible in the wintertime without a pair of snowshoes underfoot, and with no water, telephone, and electricity for miles, and little hope of getting them?

Mr. Marti is very sure on this point, as he remembers 10 years ago when he combed the region for some land with a view -- not on which to build a house but only for investment. He ran into an old Vermont farmer around here who told him he had exactly what Mike was looking for -- 80 acres of heavily wooded land and with all the world for a view.

"I told him I couldn't afford 80 acres so he sold us the 10 acres at the very top of the mountain for $500 an acre and an option for another 17 acres to the backtop road below," Mike says.

"We have since bought the 17 acres," he adds.

On a cold November evening that year Mike spent his first night on the mountain with Wayne Brown, a friend, and even got lost as they tried to hike back to the car after dark. "I learned from that moment on to respect simple rules like being equipped with a compass in unfamiliar wooded areas even though there seem to be obvious guidelines, such as a descending grade," he says.

It wasn't till the summer of '72, when Mike and Gerlinda decided to build their sky house, that Mike set about the job of designing it. They decided the house would be an octagon- shaped building with a high-pitched roof, lots of glass, and an expansive deck for enjoying the view. After all, that was why they were here in the first place.

In clearing the top, Mike says, he had to cut at least 200 trees. And then, deciding that they had to have a road from the blacktop to as close to the top as they could get, he cut down another couple of hundred trees, hired a huge bulldozer to knock out the stumps and flatten the site, and they were on their way.

Despite the road, they still had to carry everything -- cement, timbers, plywood, glass, you name it -- a few hundred feet up Hawk Mountain to the building site.

Bedrock lurks a few feet under the topsoil, Mike reports. Thus, instead of putting up a deck and building the house on top of it -- as he had thought of doing at first -- he opted to anchor the building on the bedrock itself so it could withstand the rigors of winter, including the super-high winds that can sweep the site.

"We laid out strings to locate the pillars," he goes on. "Then we had to drill into the rock and secure the concrete pillars with iron rods. You can be sure the house won't go anywhere.

"We needed water to make concrete. So we found a depressed area in the land and put up a big plastic catch to collect rainwater.

A series of 2-by-6 timbers was bolted together and plywood and glass windows put on the side.

Mike says they had planned to have full-size windows in all the walls but decided to go to smaller windows for several reasons.For one thing, the large-size glass was just too heavy to be carried uphill. Also, they didn't want to feel as if they were sitting in a display window, even if there were no neighbors outside but the animals.

Actually, the windows are two planes of quarter-inch glass fused together.

Mike had told some companies about his plan for the mountaintop retreat. In response, he was able to get the siding, roofing, and suspended fireplace without cost and the manufacturers used the house in their ads.

The house is really held together by two metal rings, one at the first level above the fireplace, and a second ring higher up which holds up the roof. It took a long time to put on the roof, because just cutting the shingles to make them fit all the corners was time-consuming and a bore.

There is no interior support, Mike explains. "The only load-bearing walls are the outside walls."

When the job was almost done -- "it's not finished even yet," Mike interjects -- they toted up the cost and figured they had already spent about $10,000 on building materials, plus their own labor. It will take another $500 to $1,000 to finish up the bathroom, put in a ceiling, and add a rug to the floor.

In retrospect, the Martis sometimes wonder how they ever did the job.

"My brother has access to a computer," Mike explains. "So before we did anything, I was concerned over whether or not the design would work. We put the problem into the computer and the reply came back 'indeterminate.' Simply, the computer couldn't solve the problem." The Martis went ahead with the job, anyway.

"When we were building the house we used a lot of braces to hold up the second level," Mike reports. "Finally, we were ready to pull out the braces. And when I pulled out the last brace, the building held up. The structure was solid and plumb."

Five years ago they added the deck.

Now, even though they are building a year-round house in Connecticut -- not alone, as in Vermont -- the Martis still plan to hang onto their "observatory in the sky."

It's a great place to get away from everything down below, they say with a smile.

"You get very efficient in doing dishes with very little water," explains Mrs. Marti, who came to the United States from West Germany 13 years ago.

"You have to limit your cooking," she adds. "No big washups here."

On a weekend, the family usually gets along on only two gallons of water, which they lug up from their car 700 feet away. "If we have friends with us," Mike adds, "we have to carry five gallons."

The water system is gravity-feed.

The mountaintop retreat is all gas, including stove, refrigerator, and lighting.

They even have a gas-powered toilet off the kitchen, which is powered by a little battery that is kept charged by a solar panel on the roof, for which they paid $250 five years ago. The panel, 14 inches square, also runs a small fan and will power a radio as well.

"It's always fun to come up here in the winter," the Martis smile -- "and often a surprise."

The snow can build up drifts that are 8 feet high and almost cover the windows. "It's a different world," Gerlinda says.

The first year, after the site was cleared, they arrived on their mountaintop without the right equipment. a storm came up fast and the Martis were caught. Visibility was bad and snow covered their tracks. After a long, harrowing downhill trek, they finally made it back to their car. "Whew!" they sigh.

From that moment on, the Martis don't skimp on anything, except water, perhaps.

Would they change anything? "Not a nail," says Mike. Gerlinda agrees.