William J. Perry went to the telephone several times during the luncheon at the CIA. When he mentioned that he had been summoned to the White House, the room full of officers and lawmakers burst into applause.

Perry, the man President Clinton chose Monday to run the Defense Department, makes the move to the secretary's office overlooking the Potomac River with support that spans political parties and uniformed services.Known as "the godfather of Stealth" for his work developing radar-evading aircraft, the Stanford University engineering professor and erstwhile No. 2 man at the Pentagon brings to the job a scholar's eye for detail and a businessman's eye for the bottom line.

He also solves a short-term problem for Clinton: how to find a defense secretary popular among military leaders and key congressional barons but still willing to carry out Clinton's defense spending cuts.

All three of those requirements appear to fall into place in the form of a bespectacled 66-year-old mathematician from Vandergraft, Pa., with a soft-spoken delivery and camera-shy demeanor.

As second in command for the past year, Perry helped Defense Secretary Les Aspin design Pentagon policies on social issues such as homosexuals serving in the military and women in combat, as well as crafting the defense budget. Perry gave no indication Monday that he would break sharply from the policies established by his predecessor.

For pro-defense members of Congress, Perry offers the hope of procurement reform, a move to simplify the way the Pentagon buys things.

For the military, Perry is an adherent of the "force multiplier" strategy: the use of high technology to overcome superior numbers in the field.

In a 1991 article he wrote for the magazine Foreign Affairs, Perry said the concept took hold during his years directing research at the Pentagon under President Carter when Warsaw Pact forces outnumbered NATO defenders three-to-one. Perry joined a move to emphasize superior spy satellites, "smart" bombs and cruise missiles, AWAC radar planes and night-vision equipment so an outnumbered force could prevail.

"An army with such technology has an overwhelming advantage over an army without it, much as an army equipped with tanks would overwhelm an army with horse cavalry," Perry wrote.

The concept reached its apogee in the Persian Gulf War, when allied forces inflicted losses on a ratio of about 1,000-to-1.

Perry became a millionaire by founding, consulting or directing defense contractors beginning in the early 1960s.

Perry saw early the value of Stealth technology. In 1964 he co-founded ESL Inc., a military electronics company that developed top-secret eavesdropping and code breaking technology.

Perry married Leonilla Mary Green in 1947. They have five grown children.