Prince Charles (search) and Camilla, the Duchess of Cornwall (search), spent their second day in Washington Thursday, visiting the National Institutes of Health, the National Building Museum and a seminar on religious faith at Georgetown University, before an evening reception hosted by British Ambassador Sir David Manning.

Wearing a navy blue suit and pearls, Camilla arrived with the prince to meet doctors and patients at the National Institutes of Health (search) in Bethesda, Maryland. The spotlight-shunning duchess was due to make a rare public speech inside after meeting doctors and patients working to treat osteoporosis.

It is an issue close to her heart. "I first became involved with osteoporosis after both my mother and my grandmother died as a result of this devastating disease," said the duchess, who is patron of Britain's National Osteoporosis Society (search).

Addressing about 40 researchers with her husband by her side, Camilla pointed out the "horrifying" statistics about the disease, which affects half of all women over 50 in Britain.

She called for greater efforts to "prevent future generations worldwide from suffering the pain and ignominy of osteoporosis."

The duchess looked nervous before the speech, tapping her notes on a table and sipping from a glass of water. Afterwards, Charles gave her a reassuring look.

The royal couple was greeted at the institute by U.S. Surgeon General Richard Carmona (search) — who almost succeeded in leading the duchess into a full-length glass window. A startled Camilla touched her nose after narrowly avoiding a collision, prompting a laugh from her husband.

At the building museum later, Charles was accepting an award for his contribution to architectural understanding — a chance, perhaps, to share his views about the importance of classical architecture and the baleful effect of modernism.

And the university seminar on faith and social responsibility could give the heir to the throne a chance to gently chide the U.S. government about its fraught relationship with the Islamic world.

The couple spent much of Wednesday with President Bush and first lady Laura Bush, highlighted by a private lunch at the White House, a visit to a local school with Mrs. Bush, and a lavish dinner with music and dancing for 130 luminaries from politics, business, sports and the arts.

The royal tour began Tuesday in New York with the couple on a mission to underscore trans-Atlantic ties and win public acceptance for Charles' marriage to Camilla, his longtime love. He and Diana divorced in 1996, and Diana was killed the following year in a Paris car crash.