IN THE PROLOGUE to her marvelous history of the sewing machine and the man who didn't invent it after all, Ruth Brandon draws a memorable picture of a commodious yellow omnibus drawn by nine horses traveling up Fifth Avenue. An orchestra perched on the outside played popular tunes, while inside, filling most of the 31 seats, rode a large family, including a litter of little children. One might infer from this picture of Isaac Merritt Singer's family bus (designed and patented by himself) that he was successful, expansive, not to say theatrical, and, in the New York of the 1850s, socially beyond the pale. All true, but what mind-blowing supplements there were to this picture Ruth Brandon relates in what is both the only biography of the most profligate multimillionaire of the age and a masterful account of one of its most significant mechanical inventions.

Isadora Duncan, mistress of one of Isaac's innumerable sons, had a hand in promoting the myth that Singer was the sewing machine's inventor. Far from it; it had been invented time and again since the mid-18th century. And though these early efforts had many essentials of a modern machine, no commercial application was attempted, except in the 1820s by an unfortunate Frenchman whose machines were smashed by jealous tailors.

When in 1850 a down-at-the-heels, 39-year-old itinerant actor named Singer came up for air, the sewing machine, though expensive and unreliable, had begun to be useful in tailor shops (cutting shirtmaking time from 14 hours to little over one). But no one was less interested in it than Isaac Singer - "a little contemptible sewing machine," is one of his first recorded descriptions.

He had been born in 1811 near Oswego to a poor German immigrant. His schooling was minimal, his training as a mechanic slapdash, and except for women, he cared only for the stage. He was crude, bullying, profane; but his tall, blond good looks and exuberant charm that worked on both sexes made him a passable actor-manager, and from the time he was 18 he roamed the theatrical circuits of the hinterlands, pausing occasionally to replenish funds by working as a day laborer.

These bouts offstage prompted the labor-saving devices he patented before he met up with the sewing machine.One, a type-carving machine, changed his life. It took him to New York, where he found a book jobber named Zieber willing to supply capital. A model was made and orders awaited. When none came, Orson Phelps, in whose machine shop the display had been set up, drew Singer's attention to the awkward sewing machines he was making for another inventor. "What a devilish machine!" Singer remarked. "You want to do away with the only thing that keeps women quiet, their sewing!" But with nothing better to hand, he applied his wits to ironing out the bugs. "I don't give a damn for the invention," he mused at about this point. "The dimes are what I am after."

The three men became partners to produce a sound, working model that Singer quickly devised by adding two new features to the basic sewing machine: a presser foot and the ability to sew curved and long, continuous seams. Singer was not only a handy inventor but a born salesman: the actor in him delighted in making sales pitches at fairs and carnivals; and he was luckily unencumbered by fine feelings. His insistence on patenting the new machine in his own name was a hint of what was to become of his partners. Phelps, badly browbeaten, was the first to be dumped, and before long Zieber was turned out too.

Once the dimes began rolling in Singer needed another sort of partner, and found him in Edward Clark, a rigorously respectable lawyer and ex-Sunday school teacher. Singer had many competitors, and Elias Howe, who had patented a machine in the 1840s, began suing the lot for royalties - successfully. From Singer alone he collected $25 on each machine sold. Every manufacturer began suing the rest; for every machine contained parts invented and patented by others. The chaos was terminated by a patent pool, into which every member paid a fee entitling him to the use of any patent. Later, such pools were to make possible radios and automobiles; they also led to antitrust laws.

For labyrinthine historical reasons that Ruth Brandon explores with aplomb and relish, the sewing machine represented the beginnings of commercial mass production, competition, and lower prices. But this miracle of progress depended on one little thing unavailable until the 1850s. The first sewing machines were handmade by highly paid craftsmen (in 1850) Singer machines cost $125; in 1870, with production-line manufacture, the price had dropped to $64, and required great skill to repair. It was interchangeable parts made on specialized, high-speed milling machinery with extremely accurate measurements that made possible the triumphs of American mass production.

For Singer the floodgates of fortune were finally opened by the unsuspected commercial genius of Edward Clark. He thought up installment plan buying (sales tripled; he paid prospective pruchasers $50 for old machines of whatever make, and junked them; he originated loss leaders by selling Singer machines at half-price to clergymen's wives. That labor-saving devices should enter the home was not Clark's idea, but it was a revolutionary one. What mischief might women make with free time on their hands? "Improve their Intellects," a cartoon sneered.

It was the Civil War that made Singer preeminent among sewing machine manufacturers, again no thanks to him. He had deplored Clark's daring initiative in setting up sales organizations and factories abroad; but it was a move that paid off handsomely; for overseas sales flourished during the war and carried the company through on a tidal wave of profits. It had become the first American-based multi-national corporation.

Singer himself was a multimillionaire with in a few years, but the Singer Sewing Machine Company by no means consumed his interests. He had other more compelling affairs. At 19 he had married and had two children; not long after, in the course of his theatrical barnstorming, he met another young woman who for 14 years shared with him a hand-to-mouth existence. Between babies, of whom there were ultimately 11, this "Mrs. Singer" played female leads opposite her lover. Luckily she was still around to enjoy success - until the day Singer divorced his wife. But the assumption that he would then marry his companion proved false.

Through a series of ludicrous mishaps, her rage and pain led to public scandal. Three more Singer families were dicovered living within a few blocks of each other - four "wives" and 17 children in all. Singer left town white things blew over, taking a new girl with him, but Clark had had enough; the partnership was dissolved.

Singer went on to marry yet another woman shortly before the birth of their first child this 18th and to build a castle in Yonkers ("The Castle").The social snubs he endured were a painful surprise, and he quit the United States for good. With four additional children, the Singers built another royal residence in England ("The Wigwam") and again Society snubbed them, though ignorant of Singer's awful past. It mattered not that he was too brash, too showy, in his sumptuous coats of blue velvet lined with pink satin; he was simply "in trade." He died in the midst of his homely, vulgar pleasures, aged 64.

Singer had never been a true achiever himself, though he reveled in what money brought him. But he had never sought money singlemindedly, any more than he had desired to relieve women of the drudgery of stitching shirts, or to revolutionize American industry.

His last family, once free from the profane source of its abounding wealth, took social steps that Singer had not dreamed of. They moved to Paris. The widow married a dubious papal count; one daughter married a prince of shining precedent and cultivation - a match their friend Proust throughly approved. Two of Singer's sons became pillars of society, while Paris, the one who most resembled his rogueish father, distinguished himself as Isadora Duncan's lover and the founder of Palm Beach.

That such a spectacular complex of history, mechanics and human comedy should have gone so long without a chronicler is astonishing. Ruth Brandon deserves the treasure she has unearthed. From meager materials she has deduced a more fascinating tale than anything she may have dreamed of at the outset. The complexities of the narrative are as elegantly articulated as those of any machine she describes, and she does it all not in 700 but in 222 sparkling pages. It's a fine romance.