D'Alembert (Jean le Rond) Traite de Dynamique, first edition, engraved title-vignette, 4 folding engraved plates, some light foxing and browning, [Honeyman 803; Norman 31; PMM 195], Paris, chez David l'aine, 1743; Traite de l'Equilibre et du Mouvement des Fluides. Pour servir de suite au Traite de Dynamique, first edition, engraved title-vignette, 10 folding engraved plates, some foxing and browning, some worming to preliminaries and errata leaf at end, with loss to text, worming to margin of plates, [Bibliotheca Mechanica 7; Honeyman 805; Norman 33], Paris, chez David l'aine, 1744, both in contemporary French mottled calf, spines gilt in compartments, paper label to upper compartment of first mentioned, slightly rubbed, 4to (2)

⁂ The first edition of d'Alembert's most famous scientific work, which includes the first statement of what is known as d'Alembert Principle.

The Traité de Dynamique is "a landmark work in the history of mechanics, reducing the science to its primary laws and principles. It consists of two parts: the first defining the general laws of motion and equilibrium, and the second covering general principles of the movement of bodies. Its statement that 'the internal force of inertia must be equal and opposite to the forces to produce the acceleration' is still known as d'Alembert's principle'. This principle is applied to many phenomena and, in particular, to the theory of the motion of fluids. It has become useful in the practical solution of many technical and mechanical problems, and is as important for the motion of bodies as is the principle of virtual velocities for their equilibrium" (PMM).

The second work is a highly important treatise on fluid mechanics: "A companion volume to Traité de dynamique in which Alembert used his principle to describe fluid motion, dealing with the current major problems of fluid mechanics. Alembert's treatment of fluid mechanics was an alternative to that already published by Daniel Bernoulli [...] and he and Bernoulli often arrived at the same conclusions" (Norman).

This copy in its second state, with pp.47-48 (fol. F4) entirely rewritten and reset in order to acknowledge the theories, among others, of Huygens, Newton, and Maupertius.