But to make it better understood, in what Method every Book explains those things, we must tell you, That in the First Book, after having treated of those things that belong to Architecture in General, by the Enumeration of the Parts that compose it, and of those that are required in an Architect, the Author explains in particular what choice ought to be made of the Seat where we ought to Build, as to Health and Convenience; after he speaks of the Foundations and of the Building of Fortifications, and the Form of Towers and Walls of Cities, he dilates himself upon the Air and Healthiness of the Situation. In the Second Book, he speaks of the Original of Architecture, and what were the first Habitations of Mankind; after he treats of the Materials, _viz._ of Brick, Sand, Lime, Stones, and Timber: After which he treats of the different Methods of laying, binding, and Masonry of Stones. He Philosophizes upon their Principles, and upon the Nature of Lime, upon the choice of Sand, and the time of cutting of Wood. The Third Book treats of the Proportion of the Temples, and of seven sorts of them which are those called _Antes_, _Prostyle_, _Amphiprostyle_, _Periptere_, _Pseudiptere_, _Diptere_ and _Hypaethre_. After he speaks of the Different spaces that ought to be betwxit every Pillar, to which he gives the Five Names following, (which in the latter Part of this Book shall be more fully explained, as well as divers Terms of Art) _viz._ _Pycnostyle_, _Systyle_, _Diastyle_, _Araeostyle_ and _Eustyle_. After that, he gives in particular the Proportions of the _Ionick_ Order, and demonstrates that it has a Proportion with Humane Bodies. The Fourth gives the Proportion of the _Corinthian_ and _Dorick_ Orders for Temples, with the Proportions of all the Parts that compose them. The Fifth treats of Publick Fabricks, _viz._ of _Market-places_, _Theatres_, _Palaces_, _Baths_, _Schools_ for Sciences, and _Academies_ for Exercises, and in Conclusion, of _Sea-Ports_; and after occasionally discourses at large upon Musick, because, speaking of Theatres, he gives an account how the Ancient Architects, were in some places of the Theatre wont to place Vessels of Brass to serve for several sorts of tunable Echo's, and augmenting the Voice of the Comedians. In the Sixth he teaches what were the Proportions and Forms of private Houses among the Greeks and Romans, as well in the City as Country; and describes all the parts of the House, _viz._ the Courts, Porches, Halls, Dining Rooms, Chambers, Cabinets and Libraries. In the Seventh he treats of the manner of making use of Mortar for Plaster and Floors; how Lime and the Powder of Marble ought to be prepared to make Stuck. He speaks likewise of the Ornaments that are common to all sorts of Buildings, as Painting; and all sorts of Colours, as well Natural as Artificial, that the Ancients made use of.