Concentrating more on disc-by-disc appreciation/analysis than on the problematic Miles Davis personality, British journalist-musician Cart works his painstaking way through four decades of jazz trumpeter Davis' remarkable ups and downs. From a middle-class Illinois background, a very young Davis found a St. Louis mentor in Clark Terry, then heard Charlie Parker and Dizzy Gillespie--sounds which drew him to N.Y., working in jazz clubs while (temporarily) attending Juilliard. His first music, then, was largely bebop, imitation Gillespie--but, with other, eclectic influences (like Lester Young), he was soon leading his own distinctive group. Acclaim and money did not follow, however, so: ""It is hardly surprising that despair and boredom made him turn to drugs."" (Carr's interpretations of Davis' offstage life throughout are superficial, somewhat protective.) Still, by 1954, he had quit cold turkey, going on to the legendary collaborations with Gil Evans, the great quintet, breakthroughs in orchestral jazz, influential music-making with John Coltrane, another decline in the early '60s, the late-'60s explorations of abstract jazz (chromatic improvisation with ""clear rock pulses"" as a ""continuum""), the mid-'70s drift into mannerism and ritual (along with more positive aspects of Eastern and electronic music). Cart gives closeup, critical commentaries on virtually all the Davis recordings, with solid (if rarely eloquent) evocations and clear, semi-technical discussions. He notes at each stage the crucial discrepancies between Davis' live performances and his studio work. And though there's an occasional lapse into hype (""Miles Davis was, almost singlehandedly, putting jazz back on the map in America""), the critiques are shrewd. As for the Davis life, however, Carr chooses to downplay the troubles with the law, the erratic behavior--with little illumination as to the nature of Davis' many physical ailments. And Carr sometimes seems limited by his British viewpoint--when discussing US social history or the jazz scene in general. With those minor limitations, then: a useful, densely detailed study.