This book, being the fourth and last of the Eco-Technology series, is an increadible finish. Naturally, all of the book deals with Viktor Schauberger, and his theories on living water, and the environement. This book, however, goes deeper into the actual inventions than the previous ones. It contains almost all of Schauberger's patent information, most of which, even though "lost" originally, is now amplified and explained by Callum Coats. The Trout Motor, the Repulsine, and the rest of Viktor's inventions fall in place like a well stacked deck of cards. You could very easily build these wonderful engines, yourself (with some help from a good machine shop, of coarse!). If you have waited for the conclusion of the series, your wait will be well worth the time. I highly suggest you pick up this copy.