DYCKMAN STREET, running across northern Manhattan, commemorates a modest family of 18th-century farmers, "almost indistinguishable from their farmer neighbors." But young Staats Dyckman did distinguish himself from his neighbors and even, to some small extent, in the jostling worlds of British and American socieity, politics and war.

When early in life he anglicized his name to States, he proclaimed a fundamental loyalty that was to determine the rest of his life. Yet he does not seem to have thought much about politics; he was a kind and likable man, of no great weight or subtlety and with few discernable principles. Possessing a good brain for accounts and a detailed memory, together with a slightly flirtatious charm and an ungovernable extravagance, he passed after some early alarms into British-held New York City and secured employment with the British army.

Dyckman was responsible for the accounts of the British quartermasters based on New York. The Peculiarity of the operation was that the quartermasters actually owned the horses and wagons which they then rented to themselves in their military capacities and at their own rates -- an irregular and costly arrangement even by comtemporary standards, when public officers were often expected to make their jobs provide much of their income. When these officers, who were his clients, later faced government auditors in London, Dyckman's mastery of the accounts game him a crucial role; and this role in turn became the source of his own livelihood and hopes of fortune. But these hopes were to be realized only late in life (he died at 51) after bitter struggles and graceless treatment by his high-ranking creditors. By then he could then do little more than lay the plans for the great house, Boscobel (called after a house once occupied by the refugee King Charles II) which he built near his old family home.

James Thomas Flexner has chosen to write his latest biography about an unknown figure as a change from writing about the great. Little-known lives not only have their own importance but help to give authentic color to their times. He exercises the popular biographer's prerogative in declining to give footnote references for his quotations. This procedure, although favored by publishers, always seems to me to underestimate the intelligence of the reading public. So historians will still have to comb these sources themselves for the same information.

His research, however, brings out much information about the supply operations which helped Britain to lose the War of Independance and about the making of private fortunes out of public duties. After the war, with Dyckman's assistance, these high-ranking men who had pocketed a large portion of funds earmarked for the transport of British forces proved extraordinarily effective in frustrating the government and crown investigation of corruption in their accounts (it lasted 24 years). But when Dyckman returned to London (he had made one long visit during the war) to try and save his own finances by getting his dues from the clients he had saved from exposure and ruin, he encountered a secretive nastiness and humiliating ingratitude. The glitter of aristocratic life had its costs, not least to an ambitious American admirer.

Does Dyckman come to life? Gradually, as the book goes on, he does, and so does his wretched sister (a victim of a bullying husband and a blundering physician) and his delightful young wife -- who emerges as the most affectionate and endearing character in the book. But it is rather a shallow life. Dyckman accepted the conventions of the world in which he succeeded in gratifying many of his own tastes and ambitions. In England, he moved among the great and titled of his day, never as an equal -- he would not have accepted that -- but as an acceptable underling. He would have appreciated more respect. But for that he come to the wrong house -- until he met the upright Scottish Lawyer, William Adam, and the great champion of all the unfortunate, William Cobbet, both of whom took up his cause. One did not have to be an American expatriate in his generation, however, to discover that independence on patronage was a slippery foundation on which to build one's hopes of economic independence or social status.

Though written by a seasoned hand, this book shows signs of hasty composition. Flexner has developed a penchant for a rather coy, semi-archaic distribution of comas and for arranging his sentences so that the reader has to redistribute the weight. One example: (of his wife's family) "The weakness of his financial situation, which had been the main reason for their opposing, to his outrage, his marriage, was now drawing him, as currents pull a disabled ship against reefs, into independence on their condescension." Or: "There was not only swapping of information but endless discussion to extract from reports often contradictory what it all portended." The elegance and assurance that once distinguished Flexner's writings seem to have shrunk into an unprepossessing and elliptical archness.

The serious reader must ask whether this effort was worthwhile. Flexner's information is genuinely interesting. His character sketches, pleasant and unpleasant, have a ring of authenticity. They also fill in details of a world whose mores do not perhaps differ from our own as much as most of us would prefer to believe. There is much redeeming family affection and friendship. These are pleasing touches, if on the whole they remain only as touches.