University police and Cambridge firemen searched Holyoke Center for more than an hour yesterday afternoon, looking for a bomb that an anonymous caller said would go off at 3 p.m.

The call-received at 12:15 p.m.-was the fourth bomb threat to a Harvard building this fall. No bombs have actually been found or exploded.

University police did not order persons to leave Holyoke Center while they conducted their search yesterday, although last month Holyoke Center was cleared twice and 1737 Cambridge Street once during similar bomb scarces.

"We're not going to ask anybody to leave unless they want to. "Robert Tonis, Chief of University Police said after the search-which he described as "superficial"-yesterday afternoon.

"It's getting ridiculous." Tonis added. "It would take two weeks to search the building thoroughly."

Prof. to Washington

Another Harvard faculty member will soon follow Henry A. Kissinger, professor of Government, to Washington to aid in American foreign-policy making.

The State Department announced this week the appointment of Louis B. Sohn, Bemis Professor of International Law, as Connselor on International Law-a newly established State Department Post.

Sohn will assist the Legal Advisor in advising the Secretary of State on the international legality of foreign policy questions.

Sohn is the "country's leading expert on all legal problems connected with the United Nations and with other multinational organizations," Derek Bok, dean of the Law School, said last night.

The new appointee will have responsibility for examining the implications-for international law and world order-of prospective programs and policies. He will also be expected to propose alternative policies.

In his planning capacity, Sohn will assist in creating new legal principles for America's relations with other countries and with international organizations.

Sohn's appointment will take him away from Harvard for only a year. He now teaches a course on "United Nations Law." and a seminar on "Problems of World Order."

Sohn was a participant in the 1945 San Francisco Conference that established the United Nations, and later served in a variety of consulting and legal positions in the U.N. In 1965. he was appointed Chairman of the Committee on Human Rights of the President's National Citizens Commission for International Cooperation.

Sohn has "a very profound background in the area of disarmament as well," according to Abram Chayes, professor of Law.

Chaves said Sohn created the idea of "raudom selection inspection" that "cracked open the inspection impasse" in disarmament negotiations.

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