Chapter XIII. Of the swelling and diminution of columns, and of the intercolumniations and pilasters

THE columns in each order ought to be form'd in such a mani nor, that the diameter of the upper part of the column may be smaller than at the bottom, with kind of a swelling in the middle.

IT is to be observed in the diminutions, that the higher the coJumns are, the less they must diminish; because the height, by reason of the distance, has that effect,

Therefore, if the column be fifteen foot high, the thickness at the bottom must be divided into six parts and a half, five and a half of which will be the thickness for the top. If from fifteen to twenty foot high, divide the diameter at the bottom into seven parts, and six and a half will be the diameter above. The same must also be observed in those from twenty to thirty foot high; the lower diameter of which must be divided into eight parts, and seven given to the upper. And so in proportion, columns of a greater altitude ought in the same manner to be diminished, as Vitruvius tells us in the second chapter of his third book,

As to the manner of making the swelling in the middle, we have no more to shew from Vitruvius but his bare promise; which is the reason that most writers differ from one another upon that subject.

The method I use in making the profile of the swell is this; I divide the fust of the column into three equal parts, and leave the lower part perpendicular; to the side of the extremity of which I apply the edge of a thin rule, "of the same length, or a little longer than the column, and bend that part which reaches from the third part upwards, until the end touches the point of the diminution of the upper part of the column under the collaring. I then mark as that curve directs, which gives the column a kind of swelling in the middle, and makes it project very gracefully,

At although I never could imagine a more expeditious and successful method than this, I am nevertheless confirmed in my opinion, since Signor Pier CATANEO was so well pleased when I told him of it, that he gave it a place in his Treatise of Arched, with which he has not a little illustrated this profession,

AB, the third part of the column, which is lst directly pers

pendicular.

The intercolumniations, or the spaces between the columns, may be of one diameter and a half of the column (the diameter being taken at the lowest part of the column.) They also may be of two, two and a quarter, three, or more diameters; but the antients never allow’d more to these spaces than three times the diameter of the column, except in the Tuscan order, where the architrave was made of timber, the intercolumniations were then very large. Neither did they ever allow less than one diameter and a half, which was the distance they usually obferv, especially when the columns were very high.

But, above all other, they approved of those intercolumniations that were of two diameters and a quarter; and they reckon’d this a beautiful and elegant manner of intercolumniation. And it ought to be observed, that there should be a proportion and correspondence between the intercolumniations or spaces, and the columns; because if small columns are placed in the larger spaces, the greatest part of their beauty will be taken away, by the quantity of air, or the vacuity between the spaces, which will diminish much of their thickness. On the contrary, if large columns are placed in small intercolumniations, the straitness or narrowness of the spaces will make them appear clumsy, and without grace. Therefore if the spaces exceed three diameters, the thickness of the columns ought to be a seventh part of their height; as I have observed in the following Tuscan order.

But if the spaces are three diameters, the columns ought to be seven and a half or eight diameters high; as in the Dorick order: If two and a quarter, the height of the columns must be nine diameters; as in the Ionick: If but two, the height of the columns should be nine diameters and a half; as in the Corinthian: And, lastly, if of one diameter and a half, the height of the columns must be ten; as in the Composite. In which orders I have taken this care, that they may serve as an example for the different intercolumniations mention’d by Vitruvius in the aforesaid chapter.

A even number of columns ought always to be placed in the fronts of edifices, that an intercolumniation may be made in the middle somewhat larger than the others, that the doors and entries, usually placed in the middle, may be the better seen. And this is sufficient as to simple colonnades.

But if loggia’s are made with pilasters, they ought to be so disposed, that the thickness of the pilasters be not less than one third of the void or space between pilaster and pilaster; and the thickness of those placed in the corners to be two thirds of the said space, that so the angles of the fabrick may be both strong and solid.

And when they are to sustain an exceeding great weight, as in very large buildings, they ought then to be made as thick as half the void, like those of the theatre of #7Vicenza, and the amphitheatre at Capua; otherwise their thickness may be two thirds of the said space, as those of the theatre of Marcellus at Rome, and that of Ogubio, now in possession of Signor Ludo-vice pe GABRIELLI, a gentleman of that city.

The £ antients sometimes made them as thick as the whole void, as those are in that part of the theatre of Verona which is not upon the Mountain. But in private buildings they mast not be less in thickness than the third part of the void, nor more than the two thirds, and ought to be square. But to lessen the expence, and to make the place to walk in larger, they may be made less thick in the flank than front, to adorn which, half columns and pilasters may be placed in the middle, to support the cornice over the arches of the loggia’s, whose thickness must be proportionable to their height, according to each order; as may be seen in the following chapters and designs.

For the better understanding of which, and to avoid my repeating the same thing often, it is to be observed, that in the dividing and measuring the said orders, I would not make use of any certain and determinate measure peculiar to any city, asa cubit, foot, or palm, knowing that these several measures differ as much as the cities and countries; but imitating Vitruvius, who divides the Dorick order with a measure taken from the thickness or diameter of the columns, common to all, and by him called a module, I shall therefore make use of the same measure in all the orders.

The module shall be the diameter of the column at bottom, divided into sixty minutes; except in the Dorick Order, where the module is but half the diameter of the column, divided into thirty minutes, because it is thus more commodious in the divisions of the said order,

From whence every one may, by either making the module greater or less, according to the quality of the building, make- use of the proportions and profiles belonging to each der, order