Locomotive

This Come Aboard quartet provides an entertaining introduction to a mode of transportation fading from use--and perhaps, accordingly, from children's experience. The board books are die-cut in the cars' traditional shapes; jigsaw-puzzlelike tabs and slots at each end enable the four to be joined together in true train fashion. A girl and boy exploring each unit discover information suitably scaled down for the books' audience--``steam makes the wheels of the locomotive turn round and round''; in the passenger car, ``everyone helps lift baggage onto the long rack.'' Two minor cavils: Walz's cheery illustrations seem somewhat dated, and unrelated scenes in Caboose and Passenger Car seem tacked on. Nonetheless, little ones may well enjoy these educational, user-friendly titles. Ages 2-5. (Mar.)