THE OTHER RUSSIA; The Experience of Exile by Michael Glenny and Norman Stone (Viking: $24.95; 475 pp.). Some of the wealthy people who left in the first great emigration after the Russian revolution literally had their identity stripped--"former people" they were called. But more recent emigres found their identities fading amid fear. "When fear grips you, you notice with horror how you stop being a human being," says an an oceanographer now living in the United States. "All your good qualities are torn away, like autumn leaves, by gusts of fear." Despite its subtitle, "The Other Russia" is more about escape than life in exile, but the tales create an involving, exuberant ode to freedom. Says Slava Kurilov of his defection by jumping ship: "For several moments I flew through the air, until I felt the waves parting, gently welcoming me into their embrace."