Besides many papers communicated to the academy of sciences, of which he became a member in 1714, he published Memoires pour servir d l'histoire et au progres de l'astronomie (St Petersburg, 1738), in which he gave the first method for determining the **heliocentric** co-ordinates of sun-spots; Memoire sur les nouvelles decouvertes au nord de la mer du sud (Paris, 1752), &c.

The coordinates thus found will in the case of a body moving around the sun be **heliocentric**. The reduction to the earth's centre is a problem of pure geometry.

The problem of determining a **heliocentric** orbit first presented itself to Kepler, who actually determined that of Mars.

His dissatisfaction with Ptolemaic doctrines was of early date; and he returned from Italy, where so-called Pythagorean opinions were then freely discussed, in strong and irrevocable possession of the **heliocentric** theory.

Contains a very clear statement of the **heliocentric** system of astronomy.

Although the **heliocentric** system is not mentioned in the treatise, a quotation in the Arenarius of Archimedes from a work of Aristarchus proves that he anticipated the great discovery of Copernicus.