At the same time, illustration on wood did not stand still. The portraits of authors diffused by the pencil of Clouet and his school were commonly put at the head of their works. We cannot say whether Clouet himself designed the portraits of Tiraqueau and of Taillemont in 1553; of Du Billon, the author of the _Fort Inexpugnable_, in 1555; Papon and Ambroise Paré in 1561; Grevin, Ramus, and others; but the precision of these physiognomies recalls the peculiar manner of the French artists of the sixteenth century. The "Poems" of Ronsard in 1586 contains a series of very clever portraits, among them that of Muret, his commentator, one of the most perfect of its kind. Christopher de Savigny, author of the _Tableaux Accomplis de Tous les Arts Liberaux_, published by John and Francis de Gourmont in 1587, is represented at full length in the frontispiece of his work, offering the book to the Duc de Nevers, to whom it is dedicated. This plate in folio, probably engraved by John de Gourmont, is the best finished that we have seen. The work of Savigny, forgotten as it may be now, had a great reputation in its own time; and Bacon took from it the idea of his "Advancement of Learning." Speaking of the Duc de Nevers, it will not be without interest to our readers to mention here a manuscript found by us in the Bibliothèque Nationale, which enables us to give an account of the work then necessary for the publication of an illustrated book. In 1577 the Duke arranged for the impression of an apologetic book, of which no trace remains; and his _intendant_ writes a long letter to him on the subject of composition and bindings. It was necessary that the work should be produced quickly, bound and gilt, for presents. The _intendant_ thinks calf will be the most expeditious covering. "It would be much the best to use black or red calf, ... well gilt above, and not vellum, which is a thin parchment that quickly shrinks." The statements of this man of business show that five proofs of each sheet were taken for typographical correction, and that twelve full days were wanted for the binding. The most interesting part of this memoir is that which treats of the engraving on wood of the portrait. The plate was designed by an artist who had afterwards gone away; it was not satisfactory, but the ornaments would pass. The _intendant_ proposes to "fix a little piece of wood in the block that could be drawn upon." Here we see correction by elimination. The pear-wood on which the original figure was engraved was to be cut out, and a square of boxwood substituted, "forasmuch as in this task the pear-wood, which is the successful, well-cut block, is the wood that is harder." [Illustration: Fig. 63.--Portrait of Christopher Plantin, printer of Antwerp. Engraved by Wierix.]