Faculty defections usually occur on a sporadic basis. But at one point earlier this spring, it looked like a mass exodus.

Within a period of a few weeks, Michael L. Walzer, professor of Government and chairman of the Social Studies concentration, and Glen W. Bowersock '57, associate dean of the Faculty for undergraduate education, announced that they would leave Harvard later in the year to join the Institute for Advanced Studies in Princeton, N.J.

Both said they looked forward to working on books in progress and to continuing research in their respective fields--pasttimes they can enjoy without the burden of teaching or administrative responsibilities.

Walzer's wife, Judith B. Walzer, assistant dean of the College for co-education and senior tutor of South House, said that she too would leave later this year, but her employment plans were undecided.

Yosef H. Yerushalmi, chairman of the Near Eastern Languages and Civilization Department, announced that he will leave Harvard to direct the Columbia University Center for Israel and Jewish Studies and become the Baron Professor of Jewish History, Culture and Society.

The Law School's only Black professor, Derrick A. Bell, earlier this year accepted an offer to become dean of the University of Oregon Law School.

William R. Rogers Jr., Parkman Professor of Divinity and professor of Psychology, will leave Harvard next month to become president of Guilford College in Greensboro, N.C.

And while the exact situation may be different, the effect is still the same: Frank B. Freidel, Warren Professor of American History, said earlier this spring that he was retiring early to become the Bullitt Professor of American history at the University of Washington in Seattle.