Here is a book on piloting and celestial navigation that approaches these subjects from a new direction. Although it has a textbook structure, the authors have attempted to give it a tutorial slant so that it can be used by individuals outside the classroom. Their goals were to provide an understanding of principles, so the sailor can invent new methods when required, as well as to give help in the practical matters, such as reading the Almanac and carrying out sight reductions while tossing about on the sea.Most books that are not intimidating tend to provide minimalist descriptions of forms and how to fill them out. Whitney and Wright have directed their writing to the sailor who is interested in the principles but is not particularly comfortable with geometry. Another feature that makes this book unique is the use of pretest questions to get readers involved in each topic before they dig in.