An account of utterly exhausting, exasperating travels mostly by rail throughout China for an entire year. Not surprisingly, this is one of Mr. Theroux's testier books. He does, however, travel to every corner of the huge country, including memorable passages on Mongolia, Xinjiang, Manchuria and Tibet (where he ended his journey). Theroux combines offhand observation, telling detail, interviews and snatches of history. Once you get past the lack of heat and hygiene, seedy hotels and Theroux's grumbling, this book is a finely detailed portrait of the diversity of Chinese landscapes and people.  (CHN133, $15.95)