Three volumes of astronomical tables, collated, compared, recalculated and enhanced from existing tables. These volumes were meant as the summa of existing astronomical tables around 1775, and allowed for individual astronomers to posses all necessary tables without having to ruin them in buying countless other books. It goes back to a proposal that Lambert presented to the Academy November 1774.
These volumes and this project is similar in spirit to the one on mathematical tables that Lambert started up in 1770 with his Zusätze. The main difference was that the astronomical table project was sponsored by the Academy, the mathematical table project was a project running on volontary contributions.