Steam hisses through the boiler. It pushes through valves and power pistons in the old engines salvaged from a Chesapeake Bay boat. Wheels turn softly, turning other wheels by means of belts, shafts and gears. One of the wheels powers a band saw with which Lona Carlson cuts a piece of brass to look like a whale.

"This machine has lots of personality," says Lona's father, Quick Carlson, inventor of the Rube Goldberg contraption. "It doesn't make a lot of noise. It's not abrasive. It's almost like a living thing."

The Carlson Bucklesmiths will demonstrate the rare art of making steam-powered brass buckles at the fourth annual Southern Maryland Farm Festival and Craft Fair this weekend in Brandywine.

"The advantage of steam is that it's the only way our workshop can be portable," says Lona.

The dream steam machine is mounted on a surplus baggage cart from Union Station that Quick Carlson purchased from Hechingers for $50. To get it to the various fairs and festivals where the Carlsons sell their buckles, Quick trailers it behind a gasoline-powered vehicle. Someday, however, the steam machine may travel under its own power. Carlson is thinking about putting an axle on the wagon and using the steam engine to turn the wheels.

"I'd probably build an under-cage to carry wood for the boiler, or maybe pull another trailer," says Quick. "It probably wouldn't go more than 5 mph. It's just in the development stage."

Carlson 's steam-powered car might look something like the first steam vehicle -- a steam-powered cannon puller invented by a Frenchman named Cugnot roughly 200 years ago. To commemorate this invention, the Carlsons' red-and-yellow steam wagon bears the legend "Bicentennial of Steam." Quick, who doesn't know whether he was named after a sailor at his grandfather's Coast Guard station named Quick Quincy Peacock, or after a solid citizen of his Michigan birthplace named Homer Spencer Quick, had a steam engine when he was a kid.

"It's always been in the back of my mind as something I wanted to investigate," says Carlson, an oceanographer by profession. When the Navy moved its oceanographic service from Suitland to Mississippi a few years ago, Carlson retired and started tinkering with steam in earnest.

"I got the engine and boiler from a small fishing boat, says Quick, picking up sticks and wood scraps from his yard and feeding the boiler. "It's energy-efficient, because I just pick up sticks I find on the ground, but it takes a lot of time."

Lona, who has finished cutting out the shape of the whale with the band saw and is now using a grinder attached to another belt on the steam machine to smooth the edges, explains the time-differential.

"If I were doing this in a shop I'd be using a 2,000-rpm rotary grinder," she says. "This is a lot slower -- about 1,000 rpms, so it will take a lot longer. The sawing time is about the same, however,"

As Lona grinds and polishes, Quick gathers wood, squirts oil here and there, and explains his machine to a visitor.

"The whistle, which kids love to pull at fairs, came from a trolley in Ohio. Trolleys were electric so the whistle ran on compressed air, but now it's powered by steam. This thing here is an oiler. It mixes a few drops of oil with the steam and lubricates the engine. The red balls twirling around are a governor.If the steam is coming through the valves to fast, centrifugal force pushes the balls out and they close the valve a little.

"There's a piston inside this chamber that pushes a rod that makes the wheels turn. I pick up the wheels at flea markets. I've probably got about $1,000 in this. Oh, this is something extra," he says, pointing to an open-ended steam pipe. "We use it for steaming crabs and corn."

Lona is polishing the belt buckle on the grinding wheel, and Quick notices that the water level in the indicator on the boiler is low.

"It really takes two people to make buckles this way," says Quick, activating an injector that will add water to the boiler from a garden hose despite the fact that the pressure inside the boiler is much greater. "One person could do it but you'd get so engrossed you'd forget to tend the boiler. One reason steam went out was that every once in a while, a boiler would blow up. We stamp each buckle with a number. Lona's almost up to a thousand. I started it, but I'm only up to 246."

When the dream steam machine isn't shaping belt buckles, it helps out around the house.

"We use it to run our barbecue spit, to grind flour, even to run our printing press," says Quick. But he dreams of someday returning the old boat engine to sea duty. When he's not busy making buckles or painting pictures or tinkering with machines, Quick builds models of the steam powered boat he hopes to build.

"My grandfather was head of a Coast Guard station in Michigan," he says. "They had some new steam boats built at Curtis Bay, in Baltimore, and he came out here and took them back. They sailed up the Hudson, along the Erie Canal, and into the Great Lakes. I'd like to make that same trip by steam."

STEAMING TO THE FESTIVAL

The Carlson Bucklesmiths will demonstrate their craft and sell their buckles (for $15 each) at the Southern Maryland Farm Festival and Craft Fair Saturday and Sunday, 11 to 6, rain or shine. Other craftspeople will be a boom-maker, a doll-maker, a candle-maker, a woodcarver, a silversmith, a peach-pit carver, and a blacksmith. There'll also be demonstrations of steam-powered threshers, a steam calliope, clowns, cloggers, a moon-bounce and food specialties like funnel cakes and bean soup. Admission $2 for adults, children free. Directions: From Beltway Exit 36-S, take Branch Avenue exit (Route 5) south 15 miles. About three miles south of the point where Route 5 joins Route 301, turn left on Cedarville Road to the Curtis farm.