Opera mechanica, geometrica, astronomica et miscellanea

I willingly took upon myself the task of collecting and arranging these items. I carefully reread the sheets, which had been examined once or twice by a proofreader, and compared them with the figures. I also cleaned various errors from certain writings that had been published in journals without the author's supervision.

I have distributed the works present here into four volumes. The first volume contains those that concern mechanics and machines; the second, geometry; the third, astronomy; and the fourth, a few miscellaneous items.

The author had published various treatises separately; many lesser writings appear scattered in journals. Among these are some that concern controversies the author had with learned men; those that pertain to the same controversy are sometimes found published in various regions, written partly in French and partly in Latin.

In editing the books that were made public separately by the author, I followed the copies he had reviewed himself, which were augmented and corrected in various places. This also applies to the few writings that were provided in the journals.

I received these copies from the Noble Lord Huygens, Lord of Zelem original: "Hugenio Zelemii Toparchâ", who had guarded these works of his uncle Christiaan with care, and who willingly granted them to me on the condition that, upon the completion of the edition, they be joined in the public library of the Academy of Leiden with the manuscripts of the same author that are kept there.