for historical pictures (577--581).--How to represent the differences of age and sex (582. 583).--Of representing the emotions (584).--Of representing imaginary animals (585).--The selection of forms (586--591).--How to pose figures (592).--Of appropriate gestures (593--600).--V. SUGGESTIONS FOR COMPOSITIONS.--Of painting battle-pieces (601--603).--Of depicting night-scenes (604).--Of depicting a tempest (605. 606).--Of representing the deluge (607--609).--Of depicting natural phenomena (610. 611).--VI. THE ARTIST'S MATERIALS.--Of chalk and paper (612--617).--On the preparation and use of colours (618--627).--Of preparing the panel (628).--The preparation of oils (629--634).--On varnishes (635-- 637).--On chemical _materials (638--650).--VII. PHILOSOPHY AND HISTORY OF THE ART OF PAINTING.--The relation of art and nature (651. 652).--Painting is superior to poetry (653. 654).--Painting is superior to sculpture (655. 656).--Aphorisms (657--659).--On the history of painting (660. 661).--The painter's scope (662). X. STUDIES AND SKETCHES FOR PICTURES AND DECORATIONS On pictures of the Madonna (663).--Bernardo di Bandino's portrait (664).--Notes on the Last Supper (665--668).--On the battle of Anghiari (669).--Allegorical representations referring to the duke of Milan (670--673).--Allegorical representations (674--678).--Arrangement of a picture (679).--List of drawings (680).--Mottoes and Emblems (681--702). The author's intention to publish his MSS. 1. How by a certain machine many may stay some time under water. And how and wherefore I do not describe my method of remaining under water and how long I can remain without eating. And I do not publish nor divulge these, by reason of the evil nature of men, who would use them for assassinations at the bottom of the sea by destroying ships, and sinking them, together with the men in them. Nevertheless I will impart others, which are not dangerous because the mouth of the tube through which you breathe is above the water, supported on air sacks or cork. [Footnote: The leaf on which this passage is written, is headed with the words _Casi_ 39, and most of these cases begin with the word '_Come_', like the two here given, which are the 26th and 27th. 7. _Sughero_. In the Codex Antlanticus 377a; 1170a there is a sketch, drawn with the pen, representing a man with a tube in his mouth, and at the farther end of the tube a disk. By the tube the word '_Channa_' is written, and by the disk the word '_sughero_'.] The preparation of the MSS. for publication. 2. When you put together the science of the motions of water, remember to include under each proposition its application and use, in order that this science may not be useless.-- [Footnote: A comparatively small portion of Leonardo's notes on water-power was published at Bologna in 1828, under the title: "_Del moto e misura dell'Acqua, di L. da Vinci_".] Admonition to readers. 3.