Britisher David Fisher's sprightly story of Tilly and a red balloon should amuse pixilated youngsters from six to sixty. Since she cannot pay the one shilling fare to ride in Professor Pennycake's magnificent red balloon, Tilly calmly sneaks into the basket and cuts herself adrift. (""She was a very vexatious child, and quite impossible."") She has a fine adventure aloft, rescues a pilot in distress, finally sinks back to earth and Professor Pennycake's impatient clutches. Vocabulary and humor are a bit sophisticated for the picture book set, but adults will be willing and eager to translate.