Side View of a #Peripteral (#Sexastyle) #Colonnade with #IonicColumns arranged in #Eustyle #intercolumniation.

In my previous post at https://pixelfed.social/p/Splines/803076419096100108, I mentioned that the consensus sweet spot for inter-column spacing was 2.25 diameters (4.5µ) between column shafts at the bottom (6.5µ axis-to-axis), except for the two middle columns where the spacing was 3 column diameters (8µ from axis-to-axis).

This variable intercolumniation is only for #colonnades in the front and back. The spacing between columns on the sides is uniform as shown in the image here.

Something worth noting in this image is the number of columns on each side. In a peripteral (sexastyle) building, there are 6 columns in the front (and back) with 5 intercolumniations between them. On the sides, it is an error to double the number of columns on the sides. Instead, the number of intercolumniations is doubled — in this case from 5 to 10, giving us 11 columns. So, the number of columns is always even in the front, and always odd on the sides (one less than twice the number of columns in the front).

On the topic of even and odd, also note that the number of steps leading up to the base of the colonnade is always odd. #Vitruvious suggested keeping the rise between 9" - 12" and the run twice that, or between 18" - 24". Note that these measurements are in physical units — a marked departure from the abstract µ = 144 units we have been using all along.

The rules for intercolumniation presented so far are known as #simpleIntercolumniation. When the Romans introduced #arches and combined them with #halfColumns to produce #arcades, the rules were adapted for the new design. Because the arches distributed the load from the beams above, it allowed for wider intercolumniation. With the addition of #pedestals, the gap was made even wider still, and the look of the complete edifice is just majestic!

With half-columns and arches, we will see some new architectural elements.