America's attic.

Poking around the Smithsonian Institution on its 150th anniversary uncovers an extremely varied assortment of fascinating items that make it possible to sense the momentum of history.

THE NATION'S treasures are too vast to find a home in a single building. Fortunately for the U.S., a generous bequest from a 19th-century Englishman provided the financing for a virtual empire of exhibition sites to house a wide-ranging collection of art and objects. Now numbering 14 venues in Washington, D.C., and New York, the Smithsonian Institution encompasses such an eclectic assortment of items--from priceless jewels to scientific wonders to historic artifacts to memorabilia of popular culture--that it is a repository worthy of the appellation, "America's Attic."

In 1826, James Smithson, a British scientist, drew up his last will and testament, naming his nephew as beneficiary. Smithson stipulated that, should the nephew die without heirs (as he would in 1835), the estate should go "to the United States of America, to found at Washington, under the name of the Smithsonian Institution, an establishment for the increase and diffusion of knowledge among men."

The motives behind Smithson's bequest remain mysterious. He never traveled to the U.S. and seems to have had no correspondence with anyone there. Some have suggested that his bequest was motivated in part by revenge against the rigidities of British society, which had denied Smithson, who was born out of wedlock, the right to use his father's name. Others have suggested it reflected his interest in the Enlightenment ideals of democracy and universal education.

Smithson died in 1829 and, six years later, Pres. Andrew Jackson announced the bequest to Congress. On July 1, 1836, Congress accepted the legacy bequeathed to the nation and pledged the faith of the U.S. to the charitable trust. In September, 1838, Smithson's legacy, which amounted to more than 100,000 gold sovereigns, was delivered to the mint in Philadelphia. Recoined in U.S. currency, the gift amounted to more than $500,000.

After eight years of sometimes heated debate, an Act of Congress signed by Pres. James K. Polk on Aug. 10, 1846, established the Smithsonian Institution as a trust to be administered by a Board of Regents and a Secretary of the Smithsonian. It conducts scientific and scholarly research, administers the national collections, and performs educational public service functions, supported by trust endowments and revenues, gifts, grants, contracts, and funds appropriated by the Congress.

In 1847, work began on the Smithsonian's...