THE WEAK AND THE STRONG (209 pp.) Gerald KershSimon & Schuster ($2.50).
Gerald Kersh, whose promise was considerable, seems determined to become no more than an English-accented historian of the Humphrey Bogart era. The bouncing vitality, rugged prose and well-turned dialogue of such books as Faces in a Dusty Picture and Sergeant Nelson of the Guard have won him a small host of admirers.
But in his new novel, Kersh's characters seem to rattle down on the reader like a hail of dime-store jewelry. They include: Gangster "Big" Brogan ("he wears . . . a ruby not much smaller than a three-volt electric...