ELIZABETH AND GEORGIANA: The Duke of Devonshire and His Two Duchesses

Despite having excellent resources (Dormer is a descendant of the Elizabeth in the title and co-edited her many journals with Chapman), gaps in the record often leave Chapman uncertain of the specifics of her story of an unusual 18th-century ménage à trois. This is especially frustrating because Lady Elizabeth "Bess" Foster is one of history's more intriguing aristocrats: separated from her husband at 24 and forced to leave their two sons with him, she took up residence with the Duke and Duchess of Devonshire, developing a deep friendship with her and carrying on a lifelong affair with him that culminated in marriage years later, after the first Duchess's death. During their affair, Bess bore the Duke two children, but, as was the custom with illegitimate aristocratic offspring, they were raised by foster parents. Amanda Foreman covered much of this territory in her terrific, bestselling Georgiana, Duchess of Devonshire. As a companion piece, Chapman's look at Bess is occasionally enlightening—she emerges as bright, curious, a dedicated keeper of journals, and an archeologist who helped unearth ancient ruins in Rome when she was nearly 60 years old. But it's never clear whether she was a pathological flirt (with a huge number of admirers) or a misguided woman with limited social options who simply accepted the best situation presented to her: that of best friend and companion to a wealthy woman whose husband had no qualms about fooling around with his houseguest. 16 pages of b&w photos. (Jan.)