The Starry Messenger

through the lenses original: "spicillis" they are carried along the refracted lines E C H and E D I. For they are narrowed, and those rays which were previously directed freely toward the object F G will now encompass only the part H I. Then, by taking the ratio of the distance E H to the line H I, the size of the angle formed in the eye by the object H I will be found through a table of sines A mathematical tool used to calculate angles in trigonometry; we shall find that this angle contains only a few minutes A minute is 1/60th of a degree. But if we fit the lens original: "specillo"; here referring to the objective lens or the telescope assembly C D with plates perforated with holes, some larger and others smaller, placing one or the other on top as needed, we shall establish at will various angles subtending more or fewer minutes. With the help of these, we will be able to conveniently measure the distances between stars separated from one another by several minutes, without an error of even one or two minutes. However, it is enough for the present to have touched upon these matters lightly and, as it were, to have tasted them with the tips of my lips; for on another occasion we shall bring to light the complete theory of this instrument original: "organi". Now let us review the observations made by us during the two most recently passed months, calling all who are eager for true philosophy to the beginnings of truly great contemplations.

Regarding the face of the Moon, which [is turned] toward our view...