On the local level, practically anyone involved in mediating between the music industry and the public stood to benefit from the largess of the publishers. Cabaret singers and dance bands were all on the take, naturally. But so was the blind busker whose one talent was winding the crank of a wheezing curbside barrel organ; ditto the guy in charge of stocking the rolls in the coin-operated player pianos in saloons and penny arcades.

Ever been invited to follow the bouncing ball across a line of lyrics on a movie screen? That's a convention established in the early 1900s by a forgotten caste of entertainers called "illustrated slide singers," paid by Tin Pan Alley to drill newly minted pop songs into the heads of nickelodeon audiences as they waited to see a silent movie. And when the movie eventually hit the screen, the house pianist would accompany the flickering images with a medley that incorporated current pop songs that he or she had been paid to plug.

There were a million other angles to the song-plugging racket, but the point stands: Payola was already a ubiquitous feature of urban life. It was also legal - although, mind you, it was interpreted even then as a symptom of the ethical bankruptcy of those in control of the music industry, who were "well known," as a disapproving journalist put it in 1924, "to contaminate anything they come in contact with with bribes of various kinds."

What payola's moralizing critics failed, and still fail, to grasp is that the music industry has always felt itself a victim, and not the perpetrator, of the system. Tin Pan Alley hated payola, and with good reason: In the teens and '20s, the major musical firms were obliged to gamble as much as $20,000 on the promotion of every hoped-for hit - an investment with a highly uncertain rate of return.....