In 1968, John Hoke, a minor Bureau of Outdoor recreation official devoted to solar energy, snakes, fish, three-toed sloths, terrarium and electricity, suggested that one way to enliven downtown Washington would be to put turtles and maybe some fish in a few of the city's barren reflecting pools.

"I'd been to London and seen the swans in Hyde Park, and so I said somewhat facetiously to a friend of mine at the Fish and Wildlife Service, why not throw turtles in some of Washington's reflecting pools, like the Simon Bolivar pool in front of Interior?" recalled Hoke, who lives in Glen Echo.

The result was three of Washington's most popular and copied mini-wildlife refuges, in former litter-filled reflecting pools, and ultimately a new job for Hoke as an urban affairs specialists, naturalist "and kind of idea man and resident Rube Goldberg," for the National Park Service here, said local Park Service spokesman George Berklacy.

Hoke convinced the Park Service to acquire the fleet of three dozens electric cars, trucks and buses that now hum quietly around the Mall and other federal parks in the nation's capital. He is ardently supporting the creation of a rooftop garden on top of Department of Interior building and is working with NASA on a project using water hyacinths to purify the lake at Kenilworth Aquatic Gardens. His office and his cellar at home are filled with electric motors, lights and solar machines he hopes to adapt for other Park Service projects.

A familiar figures as he toodles about the parks in his own small electric car, puffing on a large cigar ("the cigar pollutes, the car doesn't), Hoke says, "I'm kidded a lot and I'm sure people say behind my back "there he goes another hokey scheme,' but I don't mind." Many Park Service employees know him as the man who invented the air-conditioned pith helmets, seen and coveted during the hot summer months of last year's Folklife Festival. A solar-panel on top of the hat powered a small fan underneath.

A professional photographer and author of books on sloths and snakes and solar energy, Hoke was fired from his first government job as a foreign service officer in 1962 when a congressman called Hoke's plan to use solar energy to power an electric boat up a South American river something out of "never-never land a dreamland."

It all started when Hoke was assigned as a communications specialist in Surinam (Dutch Guinea) and saw an ad in a magazine for a solar-powered fan. He had several sent to him, "and I was mesmerizing everybody down there, including one native chief who insisted such a potent machine should be in his hands alone, and of course I had to give it to him. It's one of the most amazing demonstrations that light makes power, right there in the palm of your hand."

Hoke convinced the Agency of International Development to invest $28,000 in a small solar-powered boat engine he'd developed to travel up the rivers of Surinam and win friends and influence primitive tribesmen. It would have been the world's first solar-power boat trip but the project was killed and Hoke was forced out of AID after the chairman of a House foreign operations subcommittee attacked the scheme as harebrained and launched an investigation into other AID projects.

The solar-powered boat was later tested by the U.S Army and found to work "exactly as I said it would," Hoke said. He couldn't get a government job for two years, however, "until things quieted down" and he joined the Bureau of Outdoor Recreation.

The turtles became another turning point in Hoke's career, but they too were at first considered a harebrained idea by some Interior officials. Several things helped win the day for the turtles, said Hoke. First, the Pan American Union was asked if putting logs, plants, turtles and fish into the reflecting pool honoring South American liberator Simon Bolivar would meet with its approval, "and we were told of course, Bolivar was one of South America's greatest conservationists," Hoke said.

Then the Wilderness Society spoke to the director of the national Park Service in ty spoke to the director of the National Park Service in livar pool into a wildlife pond has saved Interior several thousnd dollars a year in maintenance costs, Hoke said, because the fish, water hyacinths and other plants keep it clean naturally, and it doesn't have to be drained and scrubbed four times a year.

The Bolivar pond had been written about in several magazines and studied by schools and park agencies around the country. Two similiar wildlife ponds have been created here since then, one outside the National Capital Parks headquarters on Hains Point and the other at the foundation by the 14th Street and the Jefferson Memorial. More could be created in fountains, pools and event the large barren lake in the middle of Constitution Gardens, which was designed to have swans, geese and ducks, similiar to London's Hyde Park, but which has no cover such as wild rice and reeds to invite them, says Hoke.

Some of Hoke's idea come from his mother, Helen. He said she was one of the first to build rooftop garden in London shortly after World War II. Also they collaborated on book on antique music boxes. The author of more than 80 books of her own, on things subjects such as ghosts, spies, dolphins, arctic seals and mammals and a popular history of fleas, Helen Hoke had been an editor for several New York publishing companies and now heads her own New York firm, Helen Hoke Associates.

John and Sylvia don't have a garden on the roof of their Glen Echo house, but Hoke's interests are visible everywhere else. "Almost everything here is electric," their 14-year-old son Larry said last week as he demonstrated the battery-powered lawn mower, carefully skirting the hyacinth-filled pond with its three dozen turtles, and then returning it through a room filled with fish tanks, terrariums, antique music boxes and bikes to Hoke's workshop . . . which is filled with just about everything else.