L’invariant de Bouguer et ses conséquences : commentaire historique

Abstract

In the second part of his prize-winning essay of 1729, Bouguer (1698–1758) considers a light ray in a spherically symmetric medium and introduces the invariant named after him. He deduces an expression of the refraction integral, leading to a table which is computed for a particular atmospheric model. He then studies the influence of the ray’s curvature on the horizon dip and predicts the hillingar effect. As a complement, we recall that the Bradley formula can be derived from the Bouguer model. This helps to understand the strong convexity of horizontal refraction versus refractivity.

Keywords

• Invariant de Bouguer
• Modèle de Bouguer
• Dépression de l’horizon
• Intégrale de réfraction
• Bradley (démonstration de la formule de)
• Réfraction horizontale
• Effet <i>hillingar</i>