The first two volumes of the entire collection are now before the public, and thus we are to a certain extent in a position to appreciate M. Ravaisson-Mollien’s qualities as an editor; we feel no hesitation in saying honestly that they are all that one could wish, and we do so the more readily because he has been attacked in the most unjust manner by M. J. P. Richter, whose English edition of the Windsor MSS. was brought out some little time ago. _Errare humanum est_ is a motto the application of which is especially true in the case of the Vinci MSS.; M. Ravaisson-Mollien himself acknowledges frankly that he may have, and that he has probably, been guilty of a few mistakes; but that the principles by which he is guided in his task are perfectly sound we do not entertain the slightest doubt, and without prolonging the discussion any further we shall merely refer the reader to the articles in the _Times_ newspaper for January last, the Italian _Nuova Antologia_ for October, 1883, and the _Journal des Savants_ for July, 1882. Our business is more especially with the second volume of the collection, but it will not be amiss to remind our friends of what are the contents of the first. In addition to several passages already published but given more correctly here, and bearing upon drawing, painting, sculpture, and hydraulics, we have the commencement of a treatise on perspective, together with essays on movement, weight, percussion, projectiles, heat, light, sound, astronomy, cosmology, and geography. The Italian text, reproduced in _fac-simile_ by photography, is printed on parallel pages with a literal French translation, and an excellent bibliographical preface describes, not only the twelve codices of the French Institute, but all the other MSS., either complete or fragmentary, which are dispersed throughout Europe.