Euler's eulogium was enhanced by his desire to quit Berlin, d'Alembert's by his dread of a royal command to repair thither; and the result was that an invitation, conveying the wish of the "greatest king in Europe" to have the "greatest mathematician" at his court, was sent to Turin.
As a rule these equations are established immediately by determining the component acceleration of the fluid particle which is passing through (x, y, z) at the instant t of time considered, and saying that the reversed acceleration or kinetic reaction, combined with the impressed force per unit of mass and pressure-gradient, will according to d'Alembert's principle form a system in equilibrium.
See Diderot's Prospectus (Muvres, iii.) and d'Alembert's Discours (Ouvres,i.) The scheme should be compared with later attempts of the same nature by Ampere, Cournot, Comte and Herbert Spencer.
So the Encyclopedie, besides giving a eulogistic article " Baconisme," speaks of him (in d'Alembert's preliminary discourse) as " le plus grand, le plus universel, et le plus eloquent des philosophes."