Book excerpt: This book is a pamphlet for the public, intended to introduce them to a new product made by the Sperry Corporation: The gyrocompass. It is a type of non-magnetic compass which is based on a fast-spinning disc and the rotation of the Earth (or another planetary body if used elsewhere in the universe) to find geographical direction automatically. The use of a gyrocompass is one of the seven fundamental ways to determine the heading of a vehicle.