CONTENTS

Letter Page

I. On the Use and Advantage of Astro-nomy. i

II. Of the Figure and Motion of the

Earth. 19

III. Of the Solar System, and the Fir-mament of the fixed Stars. 35

IV. Of the Systems of Ptolemy, Tycho

Brahe and Copernicus. 53

V. Of the System of Des Cartes. 68

VI. Of the Discoveries of Kepler andGalileo. 81

VII. Of the Newtonian System and Dis-coveries. 104

VIII. Of the Nature of the Tides. 123

IX. Of the Latitude and Longitude, and

the Methods of discovering them. 140

X. The same subject continued. 159

XI. Of the different Lengths of Days

and Nights, and the Vicissitudes ofthe Seasons. 180

XII. Of the Natural and Artificial Divi-sions of Time. 195

XIII. Of the Equation of Time, or theDifference between Mean Time andApparent. 207

XIV.