I The Force of Gravity.- II Fields of Force.- III The Potential.- IV The Divergence Theorem..- V. Properties of Newtonian Potentials at Points of Free Space.- VI. Properties of Newtonian Potentials at Points Occupied by Masses.- VII. Potentials as Solutions of Laplace's Equation; Electrostatics.- VIII Harmonie Functions.- IX Electric Images; Green's Function.- X Sequences of Harmonie Functions.- XI Fundamental Existence Theorems..- XII The Logarithmic Potential.- Bibliographical Notes.