In all sorts of Fabricks, a particular Care must be taken that they be well lighted; but the Light is principally necessary in the _Stair-Cases_, _Passages_, and _Dining-Rooms_. ART. IV. _Of the Convenient Form of Buildings._ When we are assur'd of the Convenience of the place where the City is to be Built, by the Knowledge we have of the goodness of the Air, of its Fertility, Rivers and Ports, care must be taken to make Fortifications, which do not only consist in the Solidity of the Walls and Ramparts, but principally in their Form. The Figure or Form of a place ought neither to be Square, nor Composed of Angles too far advanc'd, but it must have a great number of Corners, to the end the Enemy may be seen from all Parts; for the Angles that are so far advanc'd, are ill to be defended, and more favourable to the Besiegers than the Besieged. The Approach to the Walls must be made as difficult as possible. The most Convenient Form of Publick Places, is to have in their Breadth 2 Thirds of their Length; The _Greeks_ made about their Publick places _Double Portico's_, with Pillars near together, which Supported the Galleries above. But the _Romans_ finding this great number of Pillars to be inconvenient, placed them at a greater distance one from another, that they might have Shops well lighted. [Sidenote: _Lib. 5. Chap. 3._] The Stair-Cases of all Publick Buildings, ought to be large and streight, and to have many Entrances, to the End the People may come in and out conveniently; but we shall speak of this more largely in another place. [Sidenote: _Lib. 5. Chap. 2._] [Sidenote: _Lib. 6. Chap. 6._] The Halls where great Assemblies are to meet, ought to have their _Ceiling_ very high, and to give them their true Proportion, we must unite the Length and Breadth, and give the half of the whole for the height of the _Ceiling_. The Halls where the _Ceiling_ is not so high, must have only their breadth, and half of their length for their height. [Sidenote: _Lib. 5. Chap. 2._] In vast and high places, to remedy the Inconvenience of the noisy Echo, about the middle of the height of the Wall, must be made a _Cornish_ round about to break the course of the Voice; which without that, beating against the Walls, would beat a Second time against the _Ceiling_, and cause a troublesom double Echo. CHAP. IV. _Of the Beauty of Buildings._ ARTICLE I. _In what the Beauty of Building Consists._ _Buildings_ may have two sorts of Beauty, the one _Positive_, and the other _Arbitrary_. _Positive Beauty_, is that which necessarily pleaseth of her self; _Arbitrary_, is that which doth not necessarily please of her self, but her agreeableness depends upon the Circumstances that accompany her. _Positive Beauty_, consists in Three principal Things; _viz._ In the Equality of the Relation that the Parts have one to another, which is called _Symmetry_, in the Richness of the Materials, in the Properness, Neatness, and Exactness of the Performance.