The Sassoons, Sephardic Jews who became merchant princes of international wealth and prestige, were often called the Rothschilds of the East, and this collective biography will entail an obligatory comparison with the Frederic Morton book. Although Mr. Jackson has applied himself to all the archives, it does not seem to have the same popular reach -- perhaps because the many branches of the founding firm and the family tree are harder to keep back of. While the original patriarch was one Sason ben Salch (1750) this book begins with the story of David Sassoon who opened the Bombay counting house in 1832, was philoprogenitive and made good use of his sons, ""shuffling them interchangeably,"" and lived to see one of them--S.D.--go on to England. From then on the Sassoons moved up into the great world of snobs and nabobs: Arthur and his wife were good friends of Edward VII; Rachel owned two newspapers and was known as the Madame Midas of Fleet Street; Philip ""appeared to live in italics"" with many celebrities; Siegfried Sassoon became the famous World War I poet; and the baronetcy and direct male line of descent has just ended with Sir Victor who had a passion for the turf. . . . No particular elan, but a very respectable biography.