## Discours sur les differentes Figures des Astres ; d’ou l’on tire des Conjectures sur les Étoiles qui paroissent change de grandeur; & sur l’Anneau de Saturne. Avec une Exposition abrégée des Systemes de M. Descartes & M. Newton.

Paris: de l’Imprimerie Royale, 1732. First edition.

A beautiful copy of Maupertuis’s first book, the first work by a Frenchman to accept and expound Newton’s theory of gravitation. It confirmed Maupertuis (1698-1759) as the leading French Newtonian.

“In 1728 Maupertuis made a trip to London that was to exert a major influence upon his subsequent career. From a conceptual world of Cartesian vortices he was transported into the scientific milieu of Newtonian mechanics, and he was quickly converted to these views. From this time on, Maupertuis was the foremost proponent of the Newtonian movement in France and a convinced defender of Newton’s ideas about the shape of the earth” (DSB).

After returning to France, Maupertuis sought the assistance of the great Swiss mathematician Johann Bernoulli, who was also the greatest supporter of Cartesian vortex theory. Maupertuis travelled to Basel, where he learned from Bernoulli the advanced techniques of Leibnizian calculus and their application to physical problems. On his return to Paris, Maupertuis became Bernoulli’s representative there, soliciting his papers for the Academy, reading them publicly, correcting proofs, and sending news.

Early in 1731 Maupertuis completed a paper on rotating fluids subject to attractive forces varying as any power of distance and concluded that flattening at the poles results in all cases. Rather than submit his paper to the Academy, however, he translated it into Latin and sent it to Hans Sloane for publication in the *Philosophical Transactions*, explaining to Bernoulli: “I do not at all wish to read this piece in our meetings where there are people who are shocked simply by the word ‘attraction’.”

“Maupertuis’s initial engagement with Newton’s analysis of central forces had been somewhat tentative, especially on the question of the ontological status of gravitational attraction. But gradually he came to suspect that he could contribute novel results (with Bernoulli’s help on the mathematics) that might be noticed even beyond the walls of the Academy... By the time his paper [on rotating fluid bodies] was printed in London in the spring of 1732, Maupertuis had decided that he would no longer hide his new interests from his compatriots... He decided to [take] the unusual step of publishing his work on fluid bodies as a book, rather than presenting it to the Academy, and adding to it “a preliminary section on gravity, exposing the different ideas of the Cartesians and Newtonians”... The book embedded the mathematical problems in a discussion of Cartesian and Newtonian physics, designed to interest a broader spectrum of readers. This discussion drew on the longstanding exchange with Bernoulli, but it betrayed the extent to which Maupertuis had been thinking about the metaphysical status of the forces that his teacher considered anathema to good physics...”

“The book demystified Newton, and gravity, for French readers, by insisting that the force of impulse was no more intelligible than the force of attraction... After recapitulating the history of attempts to derive the shape of the earth, either from measurements or from theory, he embarked on what he called a “metaphysical discussion” of gravity... The apologia... accomplished two parallel objectives: to deny the absurdity or logical impossibility of attraction, and to call into question the transparent intelligibility of impulse as the cause of motion... Maupertuis went on to compare the two rival ‘systems.’ The brunt of his analysis of vortex physics rested on the failure of all attempts to match the model of swirling fluid with the observed phenomena of planetary motion, especially with Kepler’s laws of planetary motion... By the end of the chapter on vortices, he concluded that although no-one had yet managed to reconcile vortices with the phenomena, he could not declare this impossible in principle... Newton fares somewhat better, since he has shown ‘with reasonings of the most certain Geometry’ that a central attractive force, acting across a void, can be perfectly reconciled with all three of Kepler’s laws. Without recourse to equations, Maupertuis explained the synthetic power of Newton’s insight about the law of gravity, which describes the orbits of the planets, the moon, and the fall of bodies on earth...

“The ‘metaphysical’ discussion yielded to the mathematical in comparisons of different possible theoretical formulations of gravity, and their implications for the shapes of rotating bodies. Equations finally made an appearance in problems about rotating fluid bodies, the same problem recently published in the *Philosophical Transactions*. The equations did not, of course, represent Newton’s mathematics as such, but rather a Leibnizian approach to problems inspired by Maupertuis’s struggles with the *Principia*. By the end, then, the book came full circle, back to problems related to the shape of the earth, which had introduced the rival cosmologies. The problem solutions display hard-won technical credentials to legitimate the larger argument, while the chapters on Cartesian and Newtonian physics gave the calculations a broader polemical context” (Terrall).

The book concludes with a chapter on astronomical phenomena. In addition to a discussion of the deleterious effects of comets on planets and the origin of Saturn’s rings, Maupertuis included a number of speculations about the varieties of objects in the cosmos, perhaps attempting to appeal to readers’ appetites for ‘curious’ natural phenomena.

The book is rare: in 1734 Voltaire lamented that not even two hundred copies had yet been sold, although, as Voltaire told Maupertuis in a letter of 3 November 1732, ‘M. Musschenbroek said, speaking of this little book, that it was in fact the best work in physics ever produced in France.’

DSB IX: 186; M. Terrall, The man who flattened the earth. Maupertuis and the sciences in the Enlightenment, pp. 64-78. COPAC lists copies at BL, Royal Society and Southampton only.

8vo, pp [iv] 83, woodcut diagrams in text, contemporary morocco, spine gilt, hinges cracked but still strong, a very fine unrestored copy.

Item #2921

**
Price:
$3,600.00
**