Theoretical Astronomy Relating to the Motions of the Heavenly Bodies Revolving Around the Sun in Accordance with the Law of Universal Gravitation: Embracing a Systematic Derivation of the Formulœ for the Calculation of the Geocentric and Heliocentric Places, for the Determination of the Orbits of Planets and Comets, for the Correction of Approximate Elements, and for the Computations of Special Perturbations; Together with the Theory of the Combination of Observations and the Method of Least Squares. With Numerical Examples and Auxiliary Tables