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

He would then deduce them from the same foundations. We also came across some of these observations, which we omitted from the rest, both because no mention of them was made in the dissertation itself, and because we found them devoid of any explanation of their causes. Indeed, the Author was so far from bringing this project of his to completion that he did not even fully resolve everything that has a place in those earlier observations by Scheiner and Hevelius. For although he warns that he will deal with the Anthelion a luminous phenomenon opposite the sun at the end of the dissertation, we looked in vain for this, as well as for what he had meditated upon regarding the circles that appear in the sky and intersect one another obliquely.

Therefore, to remedy this deficiency as much as possible, we have added—translated from French into Latin by that same most ingenious young man—the history of a halo observed in Paris on May 12, 1667, which had already seen the light of publication around that time. For in it, those foundations which are treated and demonstrated more extensively in this dissertation on sun dogs are referred to more concisely, and mention is made of both anthelia and intersecting arcs. By comparing these foundations with those laid down here by the Author, it will be easy to infer how these omitted matters ought to be explained.

However, it made us much more anxious that he had mentioned three tables in this treatise, the demonstration of which he relegates to the end of the dissertation, even though no trace of either the tables or their demonstration appeared, although they seemed to us to be of such great importance that the matter cannot be understood without them. It was therefore necessary to derive the method for constructing these tables from the foundations laid by Huygens; this we have done, and we have appended it together with the demonstration to this little book. But later, by good fortune, a small sheet of paper fell into our hands, separated from all the rest, containing just these three tables.