Four very simple picture books on modes of transportation. In each case, Barton begins with the empty setting, "On the water," "In the sky," gives a page to each of several variations on his theme, and concludes with more detail on one, such as cruise ship or passenger jet. Specifics are well selected from the most familiar plus the most attention-grabbing among the mind stretchers. But what distinguishes these useful little volumes is Barton's use of a broad, austere black line to define large, bold areas of bright color. Always eye-catching, the design is often felicitous (of this group, Trains is the most interesting visually); and for all its simplicity, Barton includes a surprising amount of interesting, instructive detail. These will delight the youngest, and have enough meat for older preschoolers and beginning readers.