WHEN 20-year-old Elizabeth Sherman of Cleveland, Ohio arrived in Washington in January, 1878 for the social season, she was already a disappointed woman. Her first, and as it turned out, only love, for a New York lawyer, had been thwarted a year before by her family, who rejected the young suitor as neither rich nor sober enough for their "Lizzie."

Although the tall, ravishing newcomer was "better looking when 'moved' than in repose," and had what the artist John LaFarge called "a distinct interior which contradicts the exterior at moments," she was "dangerously fascinating," and all who laid eyes on her were captivated.

Her purpose in the capital, however, was not to gratify the lusts of interested beaux, but to become acquainted with her fianc,e, the lanky, dour millionaire from Pennsylvania, Senator James Donald Cameron. This loveless match to a widower 25 years her senior had been arranged in agreement with her father (an impecunious district court judge) by two Sherman uncles, John, Secretary of the Treasury under President Hayes, and General William Tecumseh of Civil War fame. It was done with the apparent acquiescence of their niece, who had decided to marry, if not for love, then for money.

Thus, with an admitted facility for "liking people on the surface while despising them underneath," Elizabeth Sherman seduced the besotted politician into a pre-nuptial agreement giving her the income from $160,000 in securities. Then, after submitting to "virtually a rape" on her wedding night, she travelled to Harrisburg to face the disapproval, indeed hatred of, six stepchildren.

For the next 19 years, until the Camerons separated in 1897, Elizabeth bore her trying existence with the heavy- drinking senator, while building an enviable reputation as Washington's most fashionable hostess. For many summers she took Martha, the only child of this joyless union, to Europe, ostensibly to broaden the shy girl's horizons.

During the long years of estrangement (Cameron did not die until 1918), Elizabeth enjoyed several flirtations: with the Russian rou,e Prince Orloff, with the sculptors Saint-Gaudens and Rodin, and with the doomed poet Joseph Trumbull Stickney. This last was almost certainly an affair. But her only enduring romantic affection was for the sage of Washington, Henry Adams.

Their close relationship was described by Henry James as "one of the longest and oddest liaisons" he had ever known. "Women have been hanged for less; and yet men have been, too, I judge, rewarded with more." It began after the suicide of Adams' wife Clover in December 1885, and continued with varying degrees of intensity until the historian's death in 1918.

Tehan's absorbing yet muddled book is based largely on the 30-year correspondence between Henry Adams and Elizabeth Cameron. Over 900 of these often poignant letters are from the infatuated Adams ("In the grip of sex no man has ever thought") to his unattainable "madonna." She became the inspiration for that great critical work, Mont-St.-Michel and Chartres (1904).

Elizabeth drank in its author's devotion "like a sponge," finding in him all that her husband lacked of refinement, gallantry, and intellectual stimulation. She responded to her admirer in lively epistolary style. Most of these letters are previously unpublished. In them she admitted to being bored with "howling swells and crowned heads as thick as blackberries," and pleaded guilty to closing up "like a jackknife when anything becomes real or sensitive." To assuage ennui and emptiness, she sucked Adams' life blood, making him understandably "more snappish than nature intended." No real passion flowed in his direction.

Frequently, however, Mrs. Cameron lured him back from his restless travels, only to shrink from his embraces when he appeared on her doorstep. The truth was, it seems, that the regal madonna found the short, strutting, bald scholar physically unappealing. As the years passed, their dilemma left them "like two exhausted swimmers, tempted to cling to each other for support, yet fearing that urgency might drown them both."

Only twice did the "urgency" of unfulfillment abate for Elizabeth Cameron. Once during World War I, when working for the Allied cause in France, and again when nursing Martha, who died of tropical dystentery at age 31, just a month and a day after Adams. This double loss left Elizabeth "nearly out of her mind with grief," and she wore only black for her remaining 26 years.

"I think of my reckless, wasted life," she had written Adams in late middle age, "with you the only redeeming thing running through it, keeping me from withering up . . ." Few but he were privy to this depair. Certainly not her adoring son-in-law, the English diplomat Ronald Lindsay, for whom she kept house in the English countryside, nor the many recipients of her hospitality. For them "she had so much charm--you could drown in it." Yet "a vein of iron beneath the surface" drove her, in spite of a loveless marriage, "to make a life" and to keep her self-respect until she died courageously of cancer at the age of 86.

It seems ungracious to quibble about such a moving story, but Henry Adams in Love has serious faults. Many of these could have been corrected by a good editor or proofreader. The text is rife with repetition. We are told twice that Elizabeth was the model for Victory in Saint-Gaudens' Sherman Monument, twice that Don Cameron played poker for the highest stakes in town, and twice that Edith Wharton was an angel of devastation to Henry James. Adams is Elizabeth's "tame cat" no fewer than 18 times in 14 pages. Theodore and Alice Roosevelt did not meet the Adamses in Egypt in the winter of 1872-73; they did not even meet each other until 1878.

Scholars will lament the lack of detailed notes and sources, and will be as perplexed as the average reader by dizzying changes of locale. We are whisked from Washington to Southampton to Paris, Dieppe, New York, London, and Cairo in the space of a few paragraphs, until we sympathize with Adams when he asks, "Where are we now? I'm sure I don't know."

The narrative is often interrupted by awkward parentheses at dramatic moments, such as the death of Clover, and there are so many lengthy quotes from superb letters that the author's prose suffers in comparison. But all this aside, the pursuit of Elizabeth Cameron is a rewarding chase, which at the very least should bring us back to the works of Henry Adams.