Christiani Hugenii Zelemii, dum viveret, toparchae opuscula postuma, quae continent dioptricam. Commentarios de vitris figurandis. Dissertationem de corona & parheliis. Tractatum de motu. De vi centrifuga. Descriptionem automati planetarii

...done a great deal, to the point that he even compiled an entire Table for every focal distance of a plano-convex lens based on it, he nonetheless later placed it among those things he had rejected from his Dioptrics. This was undoubtedly because, after the dissipation of rays which occurs in refraction was detected by the illustrious Newton, he did not judge this aberration of figure, which differs greatly from the other which arises from dissipation, to be of such importance in telescopes. For this reason, we too, who deemed it our duty to take the utmost care that nothing be done which we suspected the Author himself would not have done, rejected this discovery. However, we thought it proper to mention it in passing here, so that it might be evident from this alone with what solicitude our author attended to everything that seemed capable of contributing even a little to the perfection of telescopes.

Our author, proposing to himself the most perfect telescope, which would magnify objects at will with the greatest perfection of clarity and distinctness, found that such an attempt was hindered by the fact that an aperture larger than what is just would impede distinctness, while a smaller one would impede clarity. Hence, persuaded that there is a limit placed by Nature beyond which one cannot proceed, he achieved this: given a certain optimal telescope, he presented another that magnifies objects more, yet represents them all just as clearly and distinctly. Therefore, since the dissipation of rays contributes greatly to telescope apertures, he explains its reason; and by assuming a properly ordered telescope—such that it could neither bear a larger aperture in the outer lens nor a sharper ocular lens—he defines, for any other telescopes, the apertures and the focus of the ocular lens (given the focal distance of the outer lens) and from these, the magnification of the object according to diameter. He displays the quantity of all these in a Table, assuming a telescope of 30 feet as the norm for the others, according to the varying focal distances of the outer lens. Regarding this matter, we thought it necessary to note...