Clairaut calculated its return right within a month (p. 219).
The calculation was difficult: Clairaut discovered the means of effecting it.
The comet made its predicted nearest approach to the Sun on March 13, 1759, just one month earlier than Clairaut had computed.
Ultimately, Clairaut took into account a whole series of neglected terms, and it came out correct; thus verifying the theory.
The comet arrived at its perihelion on the thirteenth of March, only twenty-three days from the time assigned by Clairaut.
After long and persevering labour in this region, Voltaire consulted Clairaut on the progress he had made.
Clairaut made this memorable communication to the Academy of Sciences on the 14th of November, 1758.
D'Alembert, Clairaut, and others attacked the problem, but were led to just the same result.
Clairaut was then only eighteen, and was in the same year made a member of the Acadmie des sciences.
The route was always, within the limits of precision of the calculations, that which Clairaut had indicated beforehand.