PRACTICAL ASTRONOMY.EPHEMERIS.Ephemeris.- The numerical values of the coordinates of the principal celestial bodies, together with the elements of position of the circles of reference, are recorded for given equidistant instants of time in an Astronomical Ephemeris.The "American Ephemeris and Nautical Almanac" is published by the United States Government, generally three years in advance of the year of its title, and comprises three parts, viz.:Part I.-Ephemeris for the Meridian of Greenwich, which gives the heliocentric and geocentric positions of the major planets, the ephemeris of the sun, and other fundamental astronomical data for equidistant intervals of mean Greenwich time.Part II.-Ephemeris for the Meridian of Washington, which gives the ephemcrides of certain fixed stars, sun, moon, and major planets, for transit over the meridian of Washington, and also the mean places of the fixed stars, with the data for their reduction.Part III.-Phenomena, which contains predTable of Contents CONTENTS; Ephemeris; PAGE; American Ephemeris and Nautical Almanac 1; Ephemeris of the Sun; Deduction of Formulas for Computation of the Sun's Tables 2; Table of Epocbs 5; Table of Longitude of Perigee 5; Table of Equations of tlie Center% 5; Perturbations in LoDgitudc; Aberration 6; Ephemeris of the Son 6; Earth's Radius Vector 6; Sun's Horizontal Parallax 7; Sim's Apparent Semi-diameter; 7; Equation of the Equinoxes in Longitude 7; Equation of Time 9; Ephemeris of tJie Moon; Elements of the Lunar Orbit 10; Ephemeris of the Moon 12; Ephemeris of a Planet I'd; Interpolation 15; The Transit; Description of the Transit Instrument 17; The Reticle 19; The Eye-piece and Setting Circles 20; Adjustments of the Transit; 1 To Place the Wires in the Principal Focus of the Objective 21; 2 To Level the Axis 21; 3 To Place the Wires at Right Angles to the Rotation Axis 23; v; V