Fifty years ago this month, the Beatles released their second LP, just another of the things that happened on the same day as John F. Kennedy’s assassination. It’s a measure of Mark Lewisohn’s huge undertaking that, 960 pages notwithstanding, he doesn’t even get that far by the end of this first part of a projected three-volume Fabography. Tune In closes with the group just back from Hamburg, replacing the hapless Pete Best with “Richy” Starkey, and on the cusp of a career-shaping relationship with George Martin. The obvious question, as with other multi-volume biographies (Norman Sherry’s stalkerish life of Graham Greene, Robert A. Caro’s ongoing, already four-volume reanimation of LBJ, say), is whether the sheer quantitative accumulation o