Sex Primi Elementorum Geometricorum (+) Elementa Astronomica.

“Some of the benefits of the smaller format adopted by Clavius’s edition were negated by the length of the text, and the next phase of Euclidean publication during the seventeenth century saw the rapid adoption of smaller formats, culminating in a number of tiny duodecimo issues such as the 1644 Paris edition of Georges Fournier, later reprinted in Cambridge. (In note:) Issued as a duodecimo in Paris in 1644 and 1654, and in London in 1654 and 1665.” (Anja-Silvia Goeing, Early Modern Universities: Networks of Higher Learning).

Georges Fournier,  a French Jesuit priest, geographer and mathematician, served as a naval military chaplain on a ship of the line, and acquired a strong knowledge of technical and naval matters. In 1642, he published the treaty Hydrographie, where he attempted to provide a scientific foundation to the design of ships. He also authored a Treaty of fortifications or military architecture, drawn from the most estimated places of our times, for fortifications, whose original edition was published in Paris in 1649 by Jean Hénault at the Salle Dauphine of l'ange gardien. Another edition was published in 1668 in Mayence by Louis Bourgeat. His works on Euclidean geometry (Paris, 1644 and 1654) were translated into English, and gave rise to three successive editions.
Georges Fournier taught René Descartes.

Steck IV, p. 100.