Fount of democracy may lack a cornerstone : Frantic search for silver plate buried by George Washington at Capitol site turns up nothing. It could have been stolen.

For the most part, the U.S. government has proved a trustworthy custodian of national treasures. The Declaration of Independence is safe in the National Archives. The Liberty Bell is securely mounted, if cracked, in Philadelphia. And George Washington’s portrait still hangs in the White House.

Perhaps that record explains the current frenzy surrounding the search for the cornerstone of the U.S. Capitol.

Historians have combed all possible archives for clues to its whereabouts. Architects have examined plans for the ornate Palladian structure and researched 18th-Century foundation construction techniques.

And geologists have drilled deep into the ground, used sophisticated metal detectors and taken soil samples with hopes of finding traces of the silver plate buried under the stone.

So far, they have turned up nothing. And hopes are dimming that the only cornerstone George Washington ever laid will be found before Sept. 18--the 200th anniversary of the day it was lowered into the earth.

It’s probably an overstatement to say that the hunt is in any way vital to the nation. Yet it would be nice to set the record straight. After all, if we have somehow misplaced a cornerstone of the Capitol, what does it suggest about our ability to hold on to the more elusive underpinnings of our national being, such as notions of equality and freedom?

On Sept. 18, 1793, Washington crossed the Potomac River with a volunteer artillery unit and, joined by Masonic orders and others, marched along a dirt path from the grounds of what is now the White House to Jenkins Hill, the chosen site for the Capitol.

“The procession marched two abreast, in the greatest solemn dignity, with music playing, drums beating, colors flying and spectators rejoicing,” the Columbian Mirror & Alexandria Gazette reported on Sept. 25, 1793.

The crowd stood in “silent awful order” as Washington and three others lowered the “huge stone” into a trench at the southeast corner of the Capitol. It was anointed with corn, wine and oil. The Masonic grandmaster expressed hope that the “remarkable moment” would “be remembered for many ages to come.”

After a ceremony punctuated with Masonic chanting, the company retired to a barbecue to enjoy a 500-pound ox and “every abundance of other recreation.”

On the centennial of that event, a large plaque was put up in the southeast corner of the Capitol’s North Wing, a spot presumed to be correct. At a 1932 bicentennial in honor of Washington’s birth, a stone was placed near the plaque.

But in 1958, when the East Front of the Capitol was being extended and the area thought to hold the cornerstone was excavated, no rock or silver plate could be found, despite vigorous exploration. A Senate engineer, Charlie Scalla, searched for years, only to retire this summer without solving the mystery.

The Capitol’s current architectural historian, Bill Allen, thinks he knows why. In 1986, he started delving into the archives and came to the conclusion: “We had been looking for all these years in the wrong location.”

Historians thought the North Wing, which houses the Senate, was the correct location because it was constructed seven years before the South, or House, Wing. But Allen found that at the time of the dedication, plans were to build the entire structure at once. If so, he reasoned, the southeast corner was under the South Wing.

Allen’s hypothesis was met with skepticism, so a renewed search triggered by the approaching bicentennial of the Capitol began at the old suspected site under the North Wing. In keeping with strict orders not to harm the historic structure, three holes were drilled into the earth, metal detectors were inserted and soil samples were taken. But there were no traces of silver or of special stone presumed to have been used.

Then, early this year, to Allen’s delight, the search moved to the South Wing. From an electrical closet in the bowels of the Capitol, three more holes were drilled. Soil samples from the first two came back negative, but the third showed a high level of silver.

Searchers reacted cautiously and did not automatically conclude “that we had struck it rich with the plate,” said Bill Hanna, a geophysicist from the U.S. Geological Survey and a volunteer in the hunt.

As it turned out, they had not. The silver came from solder used on the drill.

So the search goes on. Private and government geologists have also tried more advanced methods--like ground-penetrating radar, electromagnetic induction and induced polarization. But none provided any clues.

As a final thrust, Hanna and a colleague plan to bore one more hole later this month from the electrical closet.

With hopes fading, Allen and the others have grown philosophical. The location “may remain a mystery to us, and it will be up to future generations to apply their expertise and techniques to solve it,” Allen said. “Or maybe it will be one of those things we will never know.”

There is also a chance, historians say, that the cornerstone and its silver slipper fell prey to a greedy 18th-Century worker before construction began. It’s a thought that wounds the national soul.

Could it be that the Capitol, the concourse of our democracy, has no cornerstone at all?