Ralph DeVore's first float was a Mother Goose for the Hagerstown Mummers parade. It was eight feet long and had two wheels.

Twenty-five years later, the floats built by DeVore Brothers for a single parade required 310 wheels.

Not to mention 50 miles of vinyl petals, 10,000 boxes of staples and more Velcro than you would want to think about.

DeVore keeps 17 floats, some of them 100 feet long, in his wife's uncle's cow barn, where he works nights and weekends. It is a big barn, 60 by 120 feet, with various sheds attached, and right now the whole place is packed to the rafters with gigantic shrouded shapes.

"We have three floats in Saturday's Cherry Blossom Parade in Washington, where we'll have the front unit, the Connecticut Connection float," DeVore says. "A week after that is the Apple Blossom Parade in Winchester, and on the fourth of May is the Preakness Parade in Baltimore. We're the only contractor for that one. Eleven units. Good parade."

It's a home-grown business. His wife Luanne and his brother Kenneth are in it with him, as well as Kenneth's son Kevin and two brothers-in-law, John Miles and Gene Krouse. They get local women to make the costumes that Ralph DeVore designs, and a neighbor up the road provides the Belgian draft horses for some exhibits. For a big project they'll have as many as 30 people working.

Ralph DeVore may work in a cow barn, but make no mistake: He plays in the big leagues.

"We're known from Miami to New York," he says. "We had eight floats last year in the Gimbels Thanksgiving Day Parade in Philadelphia on CBS-TV. This year we'll have 11."

A line of plaques stretches the width of the barn. They are from one parade. "We got over 600 prizes," one of DeVore's assistants says.

Last year Disney World ordered a float from DeVore -- a giant piano with four-foot keys that move up and down and a Minnie Mouse figure to play it.

Consider that for a moment: Disney World, the great artificer, America's official architect of fantasies. Disney World, the engineer of dreams. When Disney World wants a float built, it comes to Ralph DeVore.

"Now, some floats, they're just set on a flatbed truck," he said. "Ours are all built in. We use pickup trucks and vans and trailers and special little tractors and a '67 Ford Fairlane convertible, and we build the floats around them. I wouldn't buy a car that didn't have a trailer hitch on it. Every float has its own generator for electric power, too, because we have a lot of music and animation. You can see under here, the chain drives and stuff."

On a DeVore float, everything works. Real water flows down mountainsides. Volcanoes erupt white foam (from a fire extinguisher), bulls snort foam, Big Ben's hands turn, carriage wheels spin, figures revolve and dance, their eyes roll and their arms wave, live fish and ducks swim in tanks. One 30-foot beauty, a rainbow made of the ubiquitous vinyl petals, comes with its own working rain shower.

"The thing is to have impact," he says. "You've got to tell a story and end it, all in about 20 seconds."

DeVore has always liked exhibits that do things. When he was a teen-ager he inhabited a Frosty the Snowman figure in a Hagerstown parade and chatted up the kids along the route, calling them by name to their nervous delight.

Getting all this apparatus to the parade is an art in itself. Displays may run 16 feet wide to accommodate pretty girls, square dancers and live bands, so they must be designed to fold up in transit. The unicorn's horn has to be detachable. The whale's tail comes off. The 15-foot Pinocchio folds in the middle to get under telephone wires.

The crew hates cities like Washington where there is no storage except in vandal-prone lots and things can't be left overnight.

"Takes us two hours to set up and three to tear down. When we go to, say, Baltimore for a parade at 7 p.m., we leave at 9 a.m., and after it's over we pack until midnight, come back and put everything away and go to bed around 5 a.m. Long day. Sometimes you have to sit in the rain all day."

Just taking the caravan down the highway can age a man, for its progress is stately to say the least. "That Fairlane's gonna be valuable someday," chuckled Kevin DeVore. " 'Owned by a little old floatmaker, never driven over 40.' "

Ralph DeVore has been drawing as long as he can remember. After high school he went to work as a commercial artist and designer for Lionel Toys, and 14 years later he got a degree at the University of Maryland so he could teach art in school. He changed careers again after six years to become public relations director for the Washington County Free Library.

He is 50 now, does all the designs for his floats, enjoys being able to pick his customers and his hours, and especially likes competing with major float firms that build exhibits for around $20,000, twice what he spends.

Some companies make floats for a single show, but DeVore's are built to last. They stand crammed into the barn, covered with plastic sheets. In odd corners one notices pa pier-mache' elephants, five-foot ice cream cones, a life-size caroler, cherry trees with vinyl blossoms (they will stand on large wheeled drums whose tops come off to release helium balloons), eight generators, three dozen tires, seals, flamingos with real feathers, bunches of plastic flowers, which show up better than real ones, and reams of gold foil. There are 240 yards in a ream, and he uses 25 reams a year, all crinkled by hand.

There is an antique sleigh that came from his wife's grandfather, and an eight-foot Currier & Ives scene done in layers of wood for a 3-D effect. There are staple guns, power saws, cans of red paint ("You use lots of red for the cherry blossoms and Christmas, and white to increase the effect of size, but the real prize-winner colors are pastels, for fantasy"). There are Cinderella figures, Oz characters, a Bakst Nutcracker, circus clowns, Oriental stone lanterns, ducks and geese, a barn and silo, a bridge, a giant Neptune, a Tower of London . . .