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

The original manuscript includes a note about the difficulty of finding a suitable engraver for the figures, leading to the decision to print them separately at the end of the book so they may be unfolded easily.

the author had left, which the heirs, together with the bookseller, most kindly made available for this purpose. But since a far greater portion was yet to be completed, we could not find an artisan of the quality we desired. This was the reason why, regarding the remaining minor works, we changed our plan and used copperplate engravings, to be bound at the end of the book, yet in such a way that they can be conveniently unfolded beyond the bulk of the book.

To this Dioptrics, we have appended the Treatise on Shaping and Polishing Lenses for the construction of telescopes. Since it was written in the Dutch language, and it did not seem fitting to mix Dutch into these Latin texts, it was necessary to consider translating it into Latin. The learned Mr. Hermann Boerhaave, Doctor of Philosophy and Medicine, who teaches medicine with the highest praise at the illustrious University of Leiden, took this task upon himself and successfully brought it to completion, despite the great diligence required because many of the mechanical terms were not easily explained in Latin.

Following this, in the third place, is the Dissertation on Halos and Sun Dogs original: "De Coronis & Parheliis", written by the Author partly in Latin and partly in Dutch, which the most skillful and promising young man, M. P. Daumesnil, rendered into Latin. In this dissertation, he most ingeniously deduces the causes: first, of the various kinds of halos from water droplets containing a snowy nucleus within them; then, of sun dogs—both lateral and posterior—from similar small cylinders. He primarily proposes as models for himself two observations of halos and sun dogs made in Rome in 1629 and 1630 by the renowned Scheiner, as well as certain ones by Hevelius, which we have therefore appended to the dissertation. For many years, our Author had collected various observations of similar phenomena made in various places, with the intention that, after presenting the general causes of these phenomena, he would set them forth explained together in this little book.