Jack the Ripper was a young man of unfulfilled promise and an urge to force social reforms in London's most notorious slum, according to the author's fascinating deductions. Mr. Cullen is a London-based American reporter who re-opened the 19th century's most famous unsolved murders. (In Italy, Jack is called Giacomo-lo-Squarciatore.) He had access to contemporary coroners' reports on the five prostitutes who were the victims and dashes the image of young and beautiful girls put forward in the imaginative re-creations. They were the dregs, middle-aged and alcoholic, of Spitalsfield. The name and record of the man Mr. Cullen has decided was the Ripper are revealed for the first time anywhere and it would seem from his research that Scotland Yard shared his solution. He's cram-packed the book with every bit of folklore that has sprung up around it and has written it up with the energy and suspense that goes into the best detective fiction.