This unpublished copy of the 1678 manuscript contains a detailed summary of astronomy from a pre-Newtonian perspective. There are systematic descriptions of planets and stars, distance of planets to the earth, comets, hourly movements of the sun, solar equations, etc. The tables relate to refractions for every place at the horizon, movements of the moon, and other calculations. The plates contain illustrations to the text, one being the moon eclipse of February 13, 1710.

This is a Portuguese maritime treatise on spherical and planetary astronomy, based on the Ptolomeic system, but with presentation of the Copernican system. There are numerous diagrams and a few interesting sketches.