The idea conveyed to a Frenchman by this title would not be very clear, but it might possibly be understood that this is an infamous book, deserving to be burnt. It is a fortunate thing for _feu_ Mr. Da Cunha, that this libel on his fair name was not published in his own country (he was a Portuguese) when he was living, and when the fashion was, not only to burn books, but authors; else, so dangerous an insinuation by the Royal Society of London might have exposed him to the chance of paying dearly for their blunders and bad French. If errors of so ludicrous a nature occur in the first sheet which was so often revised, one may easily conceive in what state that part of the catalogue was which was set up, but not corrected. As a specimen I transcribe three entries in the last _slip_, containing a list of names put down pêle-mêle, of works said to be mathematical. Litheosphorus, sive de lapide Bononiensi lucem in se conceptam ab ambiente claro mox in tenebris mire conseruante liber Fortunii Liceti Genuensis pridem in Pisano, nuper in Patauino, nunc in Bononiensi Archigymnasio Philosophi eminentis. 4to. Utini, 1646. I suspected at one time, that the error arose from _Litheosphorus_ being mistaken for a star, and no attention being paid to that explanation “sive de _Lapide_ Bononiensi.” I am now satisfied that my suspicion was unfounded, and that the blunder is gravely, deliberately, and _learnedly_ perpetrated; it is not to be attributed to the mere ignorance, that _lapis_ means a _stone_, not a _star_, but to a very ingenious process of reasoning, by which phosphorus was metamorphosed into a heavenly body. To demonstrate in “as correct and complete” a manner “as the circumstances of the case will allow,” I beg to call Your Royal Highness’s attention to another work by Liceti, which does exist in the library of the Royal Society, and which was catalogued in the following manner, in the specimen now under consideration. Licetus (Fort). De Lunæ sub obscurâ luce prope Conjunctiones Libri III. 4to. _Utini_, 1641. In my proofs it stands thus: Licetus (Fortunius). De Lunæ subobscurâ luce prope conjunctiones, et in eclipsibus observata. 4to. _Utini_, 1642.