OLD JIM CANAAN by Margaret Skinner (Algonquin Books of Chapel Hill: $18.95; 287 pp.). Memphis, Tenn., in the early 1900s was no town for the timid--a brawling, boisterous river city and "the murder capital of the world." In large measure, it was Old Jim Canaan, the central character of Margaret Skinner's first novel, who made it that way. Although the book is narrated by several characters, in this promising and well-crafted story the dominant voice is that of young Jim Canaan, who views his great-uncle and namesake with both fear and disfavor. The old man--dour, crippled and enigmatic even to the large Irish family whom he supports in high style--is the undisputed vice lord of North Memphis. This is an artful, smoothly paced piece of work that chronicles the turbulent life of a closely knit Catholic Irish family. It wisely sidesteps, however, most of the heavy-handed Pat-and-Mike vaudeville routines that writers so often feel compelled to heap on the hapless Irish. A most promising debut for the talented Margaret Skinner.