The second volume was entirely devoted to astronomy, while a third volume, which was intended to complete the series and cover the subjects of optics, electricity, and magnetism, was never completed.
Ang ikalawang volume ay ganap na mapagmahal sa astronomy, habang ang isang ikatlong lakas ng tunog, na kung saan ay inilaan upang kumpletuhin ang serye at takip ang paksa ng optika, koryente, at akit, ay hindi nakumpleto.