sundials
sundials design construction and use
p 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 sundials construction and also gives a comprehensive history of time measurement . p the book begins with an introduction to cosmography through a study of the suns 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 . p 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 . p