CULTURE : Lots of Gems, No Diamond : The Smithsonian Institution is marking its 150th anniversary with a touring exhibition of 350 treasures--but the Hope diamond didn’t make the trip.

When James Smithson, an English chemist who had never visited America, bequeathed half a million dollars in the 19th century for the young United States to found in Washington “the Smithsonian Institution, an Establishment for the increase and diffusion of knowledge among man,” Congress was reluctant to accept it.

Sen. John C. Calhoun of South Carolina insisted that it was “beneath the dignity of the United States to accept presents of this kind from anyone.” It struck Calhoun and many of his colleagues as a blatant attempt by an eccentric, run-of-the-mill scientist to hallow his name. Every “whippersnapper vagabond” might try the same thing, said a member of the House.

But Congress overcame this aversion long ago, and the Smithsonian Institution, now celebrating its 150th anniversary with a national touring exhibition that premieres Friday at the Los Angeles Convention Center, is surely the apple of almost every congressional eye, even escaping most of the knives wielded lustily on Capitol Hill these days at most things cultural.

But it does not escape all knives. Although Smithsonian spending is not one of the major targets of Congress, the institution was forced to close some of its museums when budget battling between the White House and Republican congressional leaders precipitated a government shutdown in early winter.

“These are tough political times,” said I. Michael Heyman, the former UC Berkeley chancellor who now heads the sprawling institution. “But it’s not . . . aimed at the Smithsonian. We’re cherished by both parties.” Yet, the Smithsonian, as Heyman well knows, maintains that congressional regard only so long as it steers clear of besmirching cherished congressional beliefs.

Shortly after taking over the Smithsonian a year ago, Heyman, who carries the official old-fashioned title of “The Secretary,” felt forced to squelch the heart of an exhibition that questioned the wisdom of dropping the atomic bomb on Hiroshima at the end of World War II. Heyman’s hard hand in an exhibition about the Enola Gay--the B-29 Superfortress that dropped the bomb--infuriated many of his old academic colleagues, but it quieted congressional and defense establishment anger.

“There’s a difference between public and private museums,” Heyman said in a recent interview. “We do, in fact, have to be very careful. People can get sore at the Whitney [Museum of American Art]. So they are sore at the Whitney. But when they are sore at us, they say, ‘It’s our money.’ ”

Political controversy, however, is rarely on the minds of the millions of visitors who scour the buildings of the Smithsonian Institution every year for a chance to see the Hope diamond, the Apollo command module, a piece of moon rock, the original “Star-Spangled Banner,” the inaugural gowns of all the first ladies and a host of other relics from a collection that now numbers 140 million objects (if you count all the insects in the Smithsonian’s Museum of Natural History).

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For many years, the Smithsonian Institution--now a complex of 16 museums, five research institutes and the National Zoo--has been known as “the nation’s attic,” and a day or two at the Smithsonian is a must for all Washington tourists. But the museums are enormous and numerous and, in some cases, far apart (two, in fact, are in New York), and it is hard for a tourist to take in all the splendors or even all the highlights.

Some Americans, in fact, may get a better grasp of the variety of the Smithsonian by remaining at home and waiting for the institution’s traveling show to come to them. “America’s Smithsonian” is the keynote of the institution’s 150th anniversary, and the curators have packed 350 of the most popular and prized objects from almost all the museums for this unprecedented national tour of 12 cities that will be on the road for two years after its Los Angeles opening.

Heyman ruled only three pieces off-limits to the curators putting together the traveling exhibition: the single-engine Spirit of St. Louis that Lindbergh flew across the Atlantic in 1927, the tattered Ft. McHenry flag that inspired Francis Scott Key to write “The Star-Spangled Banner” in 1812 and the most visited object in the entire institution--the 45.5-carat Hope diamond donated by jeweler Harry Winston. Heyman said that the plane and flag were too fragile for travel and the diamond too tempting for thieves.

But that left a host of old favorites to take on tour. Curators put up the most resistance to shipping Lincoln’s top hat--which some accounts cite as the one he wore when assassinated at Ford’s Theater in Washington. The hat is so fragile that it has not been exhibited at the National Museum of American History for more than 15 years. But the Smithsonian conservation staff designed a protective glass-and-steel box that will house the hat all the time during the tour--whether it is in transit or on display.

Los Angeles can also count on seeing, among much else, the compass carried by Capt. Meriwether Lewis on the Lewis and Clark expedition that explored the northwest reaches of the Louisiana Purchase in 1804; the Apollo 14 command module Kitty Hawk that reached the moon in 1971; wondrous paintings by such American artists as Childe Hassam, Frederick Edwin Church, John Singer Sargent and Edward Hopper; one of the ill-fated Tucker automobiles--”the car of the future”--that never went into full production after 51 samples were built in 1948; the inaugural gowns worn by first ladies Jacqueline Kennedy, Patricia Nixon, Mamie Eisenhower and Lucretia Garfield; one of the first electric light bulbs invented by Thomas Edison; the fur coat worn by black contralto Marian Anderson when she sang at the Lincoln Memorial in 1939 after the Daughters of the American Revolution denied her the use of their Constitution Hall because of her race; a pair of the magical red slippers of Judy Garland in the movie “The Wizard of Oz” and the boxing gloves used by Muhammad Ali when he defeated George Foreman in Zaire in 1974 for the world heavyweight title.

Smithsonian officials say that the traveling exhibition will not cost the federal government anything. At a time when Congress is demanding budget tightening even of cherished programs, Heyman and his staff have persuaded four corporations to underwrite the project.

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No one is sure why Smithson, the illegitimate son of a British lord, decided to leave his fortune to the United States. He had no contact with America, and his library possessed only two books on the subject. His bequest may have reflected his resentment at Britain. He had found his way barred from the British army, church, political scene and nobility because of his illegitimacy. The Royal Society of London reportedly spurned his later scientific papers.

Despite the initial reluctance of Congress, former President John Quincy Adams, a member of the House, persuaded his colleagues to accept the bequest in 1836. The institution, largely a research center at the beginning, opened its doors 10 years later.

By 1855, the first building, known as the Castle, was completed, and it soon housed staff, laboratories, natural history specimens and paintings. The red stone building with its medieval towers and turrets, which still serves as the institution’s main administrative offices, is such an odd and familiar sight on the Washington mall that it has become the symbol of the entire Smithsonian.

Heyman, a former law professor who is the 10th secretary in the history of the institution and the only nonscientist, points out that the extraordinary growth of the institution has not been planned. “It was serendipitous,” he said. “There never has been a big game plan.” Museums have been added as benefactors donated art, specimens and buildings, and as Congress assigned new areas of expertise.

Much of the growth is relatively recent. When Heyman first came to Washington as chief law clerk to Chief Justice Earl Warren in 1958, the Smithsonian was limited in size. It comprised the castle, the zoo, the Freer Gallery of Art, the National Museum of Natural History, and the Arts and Industries Building, which housed as many historical and aeronautical items--including “The Star-Spangled Banner” and the Spirit of St. Louis--as could be crammed in.

Since then, the Smithsonian Institution has added two enormous buildings--the National Museum of American History and the National Air and Space Museum--and a host of smaller museums devoted to African art, modern art, American art, portraits, decorative arts, the black American experience, design, Asian art, postage stamps and the American Indian.

For much of its life, the Smithsonian may have taken its sobriquet--the nation’s attic--too literally. The various buildings have sometimes seemed more like attics than museums. Objects have piled up without much explanation.

Curators have obviously been trying to turn that around in recent years. The National Museum of American History’s exhibition about the World War II internment of Japanese Americans is a model of information, sensitivity and probity. But the Smithsonian evoked an ugly controversy when it decided to turn its exhibition of the Enola Gay into a study of the moral issues involved in dropping the atomic bomb on Hiroshima.

On the 50th anniversary of the bombing and the end of World War II, Director Martin Harwit of the National Air and Space Museum and his curators attempted to put together an exhibition that would explore the event and its moral issues in depth.

Although the script for the planned show tried to put the issues in perspective, its emphasis on the horrors of the bombing and its questioning of the need for it aroused the ire of veterans and members of Congress. They were especially upset that the script described World War II as “a war of vengeance” for most Americans and as “a war to defend their unique culture against Western imperialism” for most Japanese.

In one of his first acts as secretary, Heyman threw out the entire script and ordered the curators to put up a different exhibition. That show, which is still on display, includes part of the fuselage and other sections of the Enola Gay and features a video in which surviving members of the crew describe their experience. But it skirts the moral issues. There is no hint that some critics believe President Truman could have won the war without dropping the bomb. Harwit, the museum director, resigned in the wake of the controversy.

In a recent book, Barton J. Bernstein, one of these critics and a professor of history at Stanford University, accused Heyman of preventing the National Air and Space Museum “from distilling the existing scholarship on the A-bomb for popular consumption.”

But Heyman insists that his critics do not understand that a museum is not a university: “If Mike Heyman, the professor, believes X, that isn’t the voice of the university. When a show goes up at a museum, you don’t know who did it. It’s there, and people come in, and to them it’s the institution that is speaking.”

Heyman said the exhibition curators should have consulted with veterans groups extensively before planning the exhibition, noting: “You can’t take on 2.5 million American people who feel their lives were saved because Truman dropped the bomb.”

The 65-year-old Heyman regards himself as a short-term secretary.

“I don’t intend to do this for more than five years,” he said. “I’m a very good person to have at this time. The place needs someone to say no.”

There are no new buildings or museums in Heyman’s sights. He said this is not an era for expansion but a time for the Smithsonian “to get out of Washington.” The traveling exhibition that opens in Los Angeles comes out of this mood.

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“America’s Smithsonian,” Los Angeles Convention Center, Yorty Hall, 1201 S. Figueroa St. Opens Friday and continues through March 7, 10 a.m.-8 p.m. daily. Admission is free, but tickets are required. Same-day admission tickets are available at the convention center. Tickets for morning admission are distributed at 9:30 a.m.; afternoon admission at 12:30 and 3:30 p.m. Advance tickets can be ordered for a $3.50 service fee for each ticket at (800) 913-TOUR.