To this end in 1787 he visited Dover and London together with Dominique, comte de Cassini and Pierre Méchain.

[8] In 1824, Legendre's pension from the École Militaire was stopped because he refused to vote for the government candidate at the Institut National.

He developed, and first communicated to his contemporaries before Gauss, the least squares method [9] which has broad application in linear regression, signal processing, statistics, and curve fitting; this was published in 1806 as an appendix to his book on the paths of comets.

Today, the term "least squares method" is used as a direct translation from the French "méthode des moindres carrés".

Further results on the beta and gamma functions along with their applications to mechanics – such as the rotation of the earth, and the attraction of ellipsoids – appeared in the second volume.

[10] In number theory, he conjectured the quadratic reciprocity law, subsequently proved by Gauss; in connection to this, the Legendre symbol is named after him.

Legendre is best known as the author of Éléments de géométrie, which was published in 1794 and was the leading elementary text on the topic for around 100 years.

The error arose from the fact that the sketch was labelled simply "Legendre" and appeared in a book along with contemporary mathematicians such as Lagrange.