3Proportion is that agreeable harmony between the several parts of a building, which is the result of a just and regular agreement of them with each other; the height to the width, this to the length, and each of these to the whole.
4Uniformity is the parity of the parts to one another; each corresponding with its opposite, as in the human figure. The arms, feet, hands, fingers, are similar to, and symmetrical with, one another; so should the respective parts of a building correspond. In sacred buildings, for instance, the diameter of the columns and the width of the triglyphs must be similar. In the balista, by the size of the hole which the Greeks call περίτρητον; in ships, by the space between the thowls, which space in Greek is called διπηχαικὴ, we have a measure, by the knowledge of which the whole of the construction of a vessel may be developed.
5Consistency is found in that work whose whole and detail are suitable to the occasion. It arises from circumstance, custom, and nature. From circumstance, which the Greeks call θεματισμὸς, when temples are built, hypæthral and uninclosed, to Jupiter, Thunderer, Coelus, the Sun and Moon; because these divinities are continually known to us by their presence night and day, and throughout all space. For a similar reason, temples of the Doric order are erected to Minerva, Mars, and Hercules; on account of whose valour, their temples should be of masculine proportions, and without delicate ornament. The character of the Corinthian order seems more appropriate to Venus, Flora, Proserpine, and Nymphs of Fountains; because its slenderness, elegance and richness, and its ornamental leaves surmounted by volutes, seem to bear an analogy to their dispositions. A medium between these two is chosen for temples to Juno, Diana, Bacchus, and other similar deities, which should be of the Ionic order, tempered between the severity of the Doric and the slenderness and delicacy of the Corinthian order.
6In respect of custom, consistency is preserved when the vestibules of magnificent edifices are conveniently contrived and richly finished: for those buildings cannot be said to be consistent, to whose splendid interiors you pass through poor and mean entrances. So also, if dentilled cornices are used in the Doric order, or triglyphs applied above the voluted Ionic, thus transferring parts to one order which properly belong to another, the eye will be offended, because custom otherwise applies these peculiarities.
7Natural consistency arises from the choice of such situations for temples as possess the advantages of salubrious air and water; more especially in the case of temples erected to Æsculapius, to the Goddess of Health, and such other divinities as possess the power of curing diseases. For thus the sick, changing the unwholesome air and water to which they have been accustomed for those that are healthy, sooner convalesce; and a reliance upon the divinity will be therefore increased by proper choice of situation. Natural consistency also requires that chambers should be lighted from the east; baths and winter apartments from the south-west; picture and other galleries which require a steady light, from the north, because from that quarter the light is not sometimes brilliant and at other times obscured, but is nearly the same throughout the day.
8Economy consists in a due and proper application of the means afforded according to the ability of the employer and the situation chosen; care being taken that the expenditure is prudently conducted. In this respect the architect is to avoid the use of materials which are not easily procured and prepared on the spot. For it cannot be expected that good pit-sand, stone, fir of either sort, or marble, can be procured every where in plenty, but they must, in some instances, be brought from a distance, with much trouble and at great expense. In such cases, river or sea-sand may be substituted for pit-sand; cypress, poplar, elm, and pine, for the different sorts of fir; and the like of the rest, according to circumstances.