Alexander Frater (Chasing the Monsoon) steers away from polar climes and snowy wilderness, comfortably confining himself to the wide zone between the Tropic of Cancer and Tropic of Capricorn. Born in Vanuatu of British missionary stock, he's at home among scattered islands and tropical outposts, hop-scotching from the Solomon Islands to the Marquesas and Galapagos to the Caribbean, East Africa and Madagascar, and across the Indian Ocean to Sri Lanka, Burma, Laos, Papua New Guinea and Australia.  (PAC172, $14.95)