This book documents San Francisco's Auxiliary Water System for Fire Protection, conceptualized in 1906 following the devastating earthquake and fire that annihilated 25000 buildings, leaving 250000 homeless. It offers a detailed description of the system, including its two storage reservoirs, distributing reservoirs, pipe system, fire cisterns, and emergency salt water supply. The author argues that the system is the most powerful and efficient ever constructed. This book is a valuable resource for anyone interested in fire protection engineering or the history of San Francisco. It provides a detailed overview of the Auxiliary Water System and its significance in protecting the city from future fires. The author provides a comprehensive analysis of the system's design and operation, as well as its historical context. The book is well-written and engaging, making it a pleasure to read for anyone interested in the subject matter.