Note 63 — PART II. MOTION OF COMETS THROUGH THE SYSTEM.

It is by means of this formula that the table of the motion of a comet of 109 days is constructed. This table gives the time from the perihelion passage, corresponding to every degree of anomaly: by means of it we are enabled to deduce the anomaly, knowing the corresponding time; or the time, when we know the corresponding anomaly of a comet, whose perihelion distance has been determined. Kepler’s third law gives this, “that the squares of the periodic times of the planetary bodies are as the cubes of the respective distances from the sun.”