Vinson Brown, an eminent guide for the amateur naturalist tells him that ""secret worlds hide all kinds of marvelous surprises"", the most surprising of which is their amenability to the pioneer with a bit of imagination, patience and knowledge. Undoubtedly the worlds of one's immediate neighborhood, of the city and its parks, of the countryside, of other states and countries, the worlds underground and underwater and within outer space are filled with fascinating secrets, but surely the scope is a bit grandiose for one book. The experiments are extremely varied both in level and type and the subjects range from the tarantula's travels to cloud formations, water evaporation and the study of microclimates. Much too much for a single volume even for an overview of exploration possibilities. Mr. Brown has done more successful work in limited areas- How To Make a Miniature Zoo.