What are field books? Field books are diaries of surveying expeditions, descriptions of natural features, sketches of farms, town allotments and roads. Trigonometrical observations and triangulation surveys are also included. In some field books references to map and plan catalogue numbers have been added. The Field books also contain information and ties to CWC Geodetic control as well as PLS corners and other survey monuments. Many of the books are used in reference on the PLS corner cards, i.e. CWC 129, Page 2.