American Notes NEVADA

Within 30 seconds of the nuclear blast last Wednesday, a phone rang in the control room 30 miles away. Soviet Scientist Viktor Mikhailov picked it up. He punched the air to register glee at receiving precise information on the bomb yield; the control room burst into applause. The underground test the group was celebrating, however, was American, held at remote Pahute Mesa, Nev. Seven Soviets were in the control room to gauge whether measuring devices accurately calculated how powerful the explosion had been.

Next month a U.S. team will similarly monitor a Soviet nuclear test at Semipalatinsk, U.S.S.R. The idea: to make sure that both sides can verify whether a test yields more or less than 150 kilotons. If the joint- verification experiment is successful, the U.S. and the Soviet Union could at last ratify two treaties that ban more powerful tests, and the world might be a tiny bit safer.