""A Practical Introduction To Spherics And Nautical Astronomy"" is a book written by Patrick Kelly and published in 1796. The book is a comprehensive guide to the fields of spherics and nautical astronomy, which were essential to navigation in the 18th century. The book begins with an introduction to the principles of spherics, which is the study of the properties of spheres, and how they relate to the measurement of the earth and the stars. It then...