BOOKS t\NDTDE t\RTS £he epic trchipelago: ;uiagm fOHN HOSPERS fhe Gulag Archi Jelago, Volume 3, ?y Aleksandr Sol -:.henitsyn. Harper and Row, 558 pp., $17. WITH THE PUB lication of Volu~e III (Books 5-7), Solzhenitsyn's 2,000-page saga of the Soviet methods of arrest, interroga tion, and punish ment is now com plete. "It is the epic of our times," wrote the Paris newspaper Le M on de after the first publication of the Gulag in Paris (i...