THE ATOM: Nuclear Tests Stop

On the last day of October, a day that had loomed large on the calendar of those who hope for eventual negotiated disarmanent, the U.S. and Britain stopped tests of nuclear weapons. But most of the hopes had already gone glimmering before Russian threats that the U.S.S.R would go right ahead testing nuclear weapons—forcing the U.S. and Britain to resume.

Since the test stoppage came after an eleventh-hour series of small-weapons shots at the Atomic Energy Commission's Nevada Proving Grounds (see below), it brought no immediate shutdown of nuclear-weapons development. But the commitment, said the State Department and the Foreign Office, would be kept for one year, provided that the Russians 1) set off no nuclear explosions that could be detected by the free world's monitoring system, and 2) continued to negotiate toward a workable inspection system. It would be extended if the three nations, after setting up an inspection system, could make progress on a program of general disarmament.

Answering Blast. The U.S. position was laid down last week, as delegates from the U.S., Britain and the U.S.S.R. got together in Geneva's Palais des Nations for the widely heralded talks on test suspension. "The U.S.,'" said Ambassador James J. Wadsworth. the U.S. delegation chief and disarmament specialist, "enters the talks in the best possible faith to make the conference a success.'' Said British delegate David Ormsby-Gore: "In a sense we are pioneers."

But Russia's Delegate Semyon Tsarapkin was blasting away with an unacceptable proposal. Russia wanted an agreement to stop tests 1) forever. 2) right now, with talks about inspection later. And at the United Nations, Russia's Ambassador Valerian Zorin cast further doubt on Russian intentions by saying that Russia intended to keep on testing until it reached rough parity with the U.S. and Britain for 1958.

Warning Flag? Both Russians bore out Secretary of State John Foster Dulles' press conference forecast that Geneva's prospects looked dim. Some Western experts, said Dulles, thought they knew why. Their theory; the long, friendly talks about nuclear-test inspection systems between U.S. and Russian scientists at Geneva last summer ''opened the eyes of the Soviet Union to the fact that our own knowledge was considerably greater than theirs about nuclear weapons. They realized that they were considerably behind in this matter, and therefore they lost interest in the suspension."