Gr 3-6 The ten-year-old sleuth, accompanied by his ``Watson,'' Sally, solves ten more cases which plague Idaville. Readers are encouraged to guess the solutions, which are printed at the end of the book. Each case is a short five pages in large type, with a simple plot. The solutions usually follow logically from the set-up, and readers just have to pay careful attention to the clues. There are a couple, however, that depend upon special knowledge that a child might not have. Still, readers can enjoy the revelation and admire Encyclopedia for knowing. Much of the evidence wouldn't stand up in a court of law, but who cares? The villain usually confesses anyway. Idaville has a small town atmosphere, and everyone seems to utter cute, folksy turns of phrase, some of them real groaners like, ``she could move in the best circles without going straight.'' One full-page pen-and-ink drawing accompanies each story, and a half-page illustration appears with each solution. No doubt the book will be as popular as the other books in the series, and it won't let fans down. Annette Curtis Klause, Montgomery County Libraries, Md.