THE GOLDEN CENTURY OF ITALIAN OPERA: FROM ROSSINI TO PUCCINI by William Weaver (Thames & Hudson: $27.50). William Weaver traverses in skimming coffee-table book fashion the glorious 110-year period of opera from "Il barbieri di Siviglia" to "Turandot." Vignettes about audiences, impresarios, singers, composers, mistresses and critics command attention, especially when they are quoted from eye-witness accounts. But Weaver creates problems by covering the material in strict chronological order--which means shifting from one composer, singer, theater or geographical area to another before a coherent picture or assessment of any one can occur. At times, this process also results in a numbing amount of purely incidental information. Yet for all the detail, the lives, achievements and struggles of the composers remain remarkably simplified. Some portraits inevitably remain painful, shocking reading, however: Bellini's lonely death from chronic amebiasis at age 34; Donizetti's final illness and death from syphilis at 50, and the obscure, crushing poverty that embraced some of the singers who had created the great, timeless roles.