A bloodstained Pony Express saddlebag.

Fonzie's jacket.

A 19th-century Cleveland schoolroom.

Dick Clark's bandstand.

The Dudgeon 1866 steam wagon.

Antique cat's-eye marbles.

A Nazi Enigma code machine.

Archie Bunker's chair.

A World War II Army barrack.

Charlie McCarthy.

. . . There are those who ask if indeed there is anything the Museum of American History does not collect.

And the answers they get tend to surround the question rather than confront it.

"We're not an art museum," says director Roger Kennedy, "we're not about how pretty things are. We're not a science museum, we're not about how things work--except to the extent of how things and people work in connection with each other.

"We're trying to convey to the American people some heightened sense of their common experience. It's why we changed the name: We're just trying to be the best damn American history museum in the world."

This summer most of the second floor will be closed as a far-ranging 10-year plan goes into effect, bringing new order to the vast collection, making all those things say something to the people who see them. And in case you didn't know: A museum exhibit can say plenty. Take the FDR show, which is (actually by coincidence) twinned with the George Washington show.

"Both of them together form a study of how you made yourself into a public figure in the 18th or 20th centuries," Kennedy says. "In Roosevelt, we see the enormous changes that radio made in the '30s. They weren't all good, either. Hitler was a master of radio too, don't forget. FDR's Fireside Chats were a tremendous device to reach the public over the heads of the government. But there was an element of Big Brother there, too. You compare it with Washington and see how he deliberately set out to present himself to the public, using the devices available to him, and you learn something, not only about the men themselves but about human psychology."

There are people who find the Museum of American History (ne'e History and Technology) simply too much. All that stuff. All those words. The job of the curators is to give it shape.

"The farther back you go, the fewer things you have to deal with," says Carl Scheele, curator of the community life division. "We're working on a big history of modern America "Travels Through 20th Century America" , and there is a huge amount of material to choose from. There's also another problem: It's a throwaway era. Things go so fast. Try to find a Hula-Hoop today. In the 18th century people wore their clothes out and then put them away. Today they're thrown out. Part of our function is to preserve samples of our material culture as we go along."

Hence the old Playbills, Supremes costumes, TV clips and milk cans. Samples of might-have-beens and also-rans are valuable, too, because you can learn from them. You see some old cylinder records, long since superseded by discs. Yet cylinders make a better recording. You ask: Why were they abandoned? Answer: Because manufacturers found discs easier to store.

Now, simply laying out a bunch of things won't do. People won't look at them. So you put them together in an environment. Scheele wanted an authentic schoolroom, to depict multi-ethnic American urban education as an institution. He went to Cleveland because it had a nice ethnic mix, found that three old schools were about to be demolished. He picked one built in 1883, had it shipped east in pieces, wrote the company that had mixed the paint for it and got the original color formula from its files. From old photos he learned where the desks and radiators went.

Another time Scheele drove 10,000 miles through 13 states searching for "a building that hadn't changed in a century," finding it at last quite close to home: the post office at Headsville, W.Va. Installed near the museum entrance, it is crammed with antique tobacco tins, groceries and hardware, and people love it. They point out the faded Clabber Girl box or the Nehi bottle to the kids. "I remember that."

If you had all those things laid out on a shelf somewhere, nobody would give them a second look.

The museum has many lifesize dioramas: a sharecropper's cabin, a '30s kitchen, a Revolutionary War general's tent, a New England house (to be a featured exhibit in the renovation), a mock-up section of the Stanford Accelerator in the massive exhibit of "atom smashers." They are everywhere, luring you into their silent worlds, inviting you to feel homesick for places you have never been.

But it would be dull if all the exhibits were on the same scale. The trick is to vary scale and pace. The sports display has a breakneck film montage of yesterday's stars in action plus a bewildering miscellany of things stuck all over the walls. The George Washington show is spare and stately.

"There are so many ways you could present the 20th century," Scheele observes. "The problem is how to get across a sense of 20th-century ideas through a display of 20th-century things. There's so much to choose from, in storage here and in the warehouse in Suitland: Collecting is a growth business. A good way to build a collection is to have a specific end in mind, like this 20th-century show."

It is due in 1989 or so, he adds. Time ticks slowly in a museum.

Some exhibits are as palpable as a storefront. Some are subtle, conceptual. Elizabeth Harris, codirector of the social and cultural history division, did a history of Braille.

"You can't imagine how hard they found it to design an alphabet for the blind. People couldn't grasp that letter symbols can be anything you want. A pencil could be 'a,' a hairpin 'b' and so on. In the end, they had to have blind people invent the alphabet."

For someone as deeply involved in language and letters as Harris, herself a printer, this discovery led to speculation on the relation of language and thought, Gutenberg and cattle brands, the new technology that has freed us from the type block and allows letters to swirl and curve and balloon. Getting people to think about these notions takes a lot more than a row of labeled Braille samples in a case. Time Trials

How does a major exhibit happen?

Margaret Klapthor started talking about a George Washington show in 1970. The museum, she reminded her colleagues in the military history department, is rich in Washingtoniana, having been given a quarter of Mount Vernon's furnishings--chairs and tables, silver, glassware, china, pots and pans--by an heir, and much more on loan. It was scattered among various exhibits.

But the project lost out to the Nation of Nations show. She tried again six years ago, and again in 1978. This time it moved ahead. Approval came from "Upstairs," meaning the museum hierarchy, and finally from "Across the Mall," the universal euphemism for Smithsonian Secretary Dillon S. Ripley.

"It was cranked into the budget, and by '81 things looked good," says Klapthor, who is now curator of the political history division. "All this time I'd been working on the concept, estimating costs, square footage, the site and so forth. We began making overtures to Mount Vernon and other museums for stuff. Everything takes a long time here."

Note: As a measure of her farsightedness, she took on a museum studies graduate, Howard Morrison, as her understudy, in case her arthritis should sideline her far down the road.

"You start with object lists. See what's available and where it would fit into the show. You figure what you want to say and how to say it."

The lists, one page per item with photo and dimensions, are the basic tool. From them come the catalogue (this one, funded by United Technology, has 150 color plates and 232 pages) and the script, very much like a TV script, alternating narrative and descriptions of objects, tying it all together.

Construction started in June 1981 after the site had been changed four times. Objects were assembled, and those that needed fixing were sent to the conservation department. Frames and mountings were designed and built. By December things were being moved into the hall. The show was to open in February. Fashion-Plate President

"The fun part is the concept," Klapthor says. "We try to tell historians that objects are great primary history sources. For instance, we studied Washington's orders to England for clothes and furniture, and compared them to what he actually got. He asked for the most fashionable stuff. He was extremely conscious of the English fashions."

Morrison takes up the story. "From this, we focused on his sense of style. We saw that he was deliberately setting a scene for himself. From the diaries and letters we learned that he saw the world as a theater and himself as a figure on the stage who hoped to close each act with applause. It was his life metaphor. It wasn't just a fac,ade but how he organized his whole life."

So the show views Washington in terms of act and scene, in stages, as he played the part of gentleman squire (modeled on his neighbors the Fairfaxes), general (modeled on British generals he had met in the French and Indian War) and finally president. There was no precedent here, so he moved very cautiously, planning with great deliberation which functions he would attend, what he would wear, how he would act so as to appear a leader but never a king.

"Read?" Morrison laughs. "We read everything. The biographies, the five-volume diary, thousands of letters."

In the end, they used 75 percent of the materials available, 657 objects. The object lists filled eight thick volumes. Seventy-five lenders provided 220 of the objects.

It is a long way from concept to concrete. A solid year before the show opened, Nadya Makovenyi, the exhibit designer, got word of the project. Working from a one-page rough draft of the script and some object lists, she started making her plans.

"Everything was going on at once," she says. "You're refining it all this time, you're getting a better feel for the objects and their relationships. After the final location is decided, the load comes onto the design department. I hire an assistant, get the object lists, the dimensions, figure whether to use a case or put something on the wall. Now I get an expanded script from Margaret, more labels, a better idea of the form. I do a floor plan and maybe a scale model to see how the spaces work together. Meanwhile I've been thinking about molding designs, frames, floors."

There were 8,500 square feet to play with. The give and take between departments was constant: Klapthor wanted a whole set of side chairs, wound up with one. For the colors, Mount Vernon had to be consulted. Finally, Makovenyi turned the show over to the production people.

"We've developed this system over the last 20 years," she says. "It works."

Next January it will all be taken down.

By then, 5 million people will have seen the George Washington show. Some will have trudged right past it, some will have learned from it, some will have been changed by it.

"This museum is a can opener to American history," says Roger Kennedy.