"We call her the lace lady, even though her diress was really brocade and velvet," explains Ann Etches, manager of the London Brass Rubbing Centre in the nether regions of Washington Cathedral. Both Elizabeth Ransom, 11, and her sister, Katherine, 9, want to do rubbings of this woman named Margaret Peyton who put on her best dress and had her image cast in brass back in the 1400s. But since only one brass image of Peyton -- copied from a larger original in a church in Cambridgeshire -- is available at the time, Etches diplomatically tries to interest Katherine in another subject.

"That's Henry Stafford,"she says, pointing to a brass knight. "He's bigger -- there's a lot of rubbing for small fingers there. But he has nice armor, hasn't he?"

After inspecting dozens of knights, ladies, religious scenes and animals, Katherine settles on another 15th-century woman, Margaret Spycer.

Etches approves the choice, noting that the brass figure has distinctly raised edges, which makes for a well-defined rubbing, and that it's not so big that a child will tire of the work before it's finished.

"Brass rubbing became the fashion in the 13th century -- shortly after brass was invented -- and died in the 16th century. We don't know why it went out of fashion, but it came into fashion again in the beginning of this century. Most of the subjects were quite ordinary people -- knights and their ladies and wool merchants and some ecclesiastical gentlemen and lawyers. Their portraits were placed on the floors of small medieval churches."

After being walked on for centuries, many church brasses are in such bad shape that church authorities don't allow them to be rubbed. So the London Brass Rubbing Centre has made copies of them. Some are exact-size replicas, made by taking a wax mold of the original, building it up with epoxy resin, and putting brass on top. Some are copies, smaller than the originals. The Centre pays annual royalties to churches that let them make reproductions of their brasses, and these royalties help keep many churches going, Etches says.

To get the girls started, Teches tapes 100 percent rag paper tautly over the brasses. Katherine's paper is black, but Elizabeth, despite a warning that it's hard to erase your mistakes on white paper, chooses white.

"First you take a piece of cloth with your fingers and run it over the outlines of the brass to mark them on the paper," she tells. them. Then she lets the kids pick out peices of beeswax, which have metal resins in them and come in metallic colors. Using the flat side of the wax, the girls trace the outline of the brass.

"Now take the shoulder of the wax -- the curved part -- and make short, hard up-and-down strokes over the whole brass, always going in the same direction," she says. "When you're finished with that, you'll want me again."

"It's just like doing a leaf, but a little more complicated,"says Elizabeth.

"I've rubbed pennies," says Katherine.

Armed with such experience, the girls proceed to rub, using pieces of cardboard to avoid going outside the lines.

"Is 1442 the year she was born?" asks Katherine. No, replies Etches, that was the year the brass image was made.

"She looks tired," remarks Elizabeth. "I guess she had to stand still a long time."

In less than 15 minutes, the portraits are completed and the girls polish them with cloths. All around them, in every cranny of the cathedral crypt, people are rubbing. One couple is rolling up a life-size rubbing of a knight. A five-year-old is completing a presentable rubbing of a lamb.

"The animals were taken from the bottom of the brasses," explains Etches. "It looks as if the people were standing on the animals, but of course they weren't. Men were often pictured with a lion, the symbol of courage, while women were often pictured with a dog, the symbol of faithfulness."

Etches removes the paper from the brasses, and the girls erase their stray marks.

"We don't really know who did these brasses," says Etches. "They were illiterate people generally, and couldn't have signed their names. We do know that a 14-year-old apprentice did this brass of the Adoration. It's small enough so that some people have made Christmas cards out of it... Do you notice how many of the knights have their legs crossed? It was once thought that meant that they had been successful in the Crusades. But a historian did some research and found that many of the knights with crossed legs had never gone to the Crusades. It was simply a more comfortable pose."