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by Denis Savoie (Author)
Sundials, which decorate church walls, public plazas, and elegant gardens, are first and foremost astronomical instruments. Before understanding how sundials work, one must first understand the apparent motion of the Sun in the sky. In this book, Denis Savoie presents the basics of astronomy required to understand sundials and describes how to design and build your own classical sundial. Written to engage all levels of science readers, the author shows the calculations involved in the sundial's construction and also gives a comprehensive history of time measurement.
The book begins with an introduction to cosmography through a study of the Sun's annual and diurnal motions. The Celestial Sphere and the local Celestial Sphere, the hour angle of the sun and the equation of Time are all discussed. The author then moves to a brief history of both sundials and time, giving the general principles behind the sundial, the conversion of solar time to clock time, and discussing the local meridian line. The gnomon and the use of its shadow are also explained in detail. In addition, many types of sundials and their different uses are described. These include the polar, horizontal, and north-facing sundial, just to name a few.
The practical and observational aspects of sundials will enable readers to create custom-made sundial of their own, adding whatever special features they wish to include. Most of these designs have been tested by people with no previous knowledge of astronomy. To aid the reader, the book is full of clear and instructive illustrations and diagrams.
