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.

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

Ever since prehistoric architects at #Stonehenge designed rock columns and labored to lift the heavy rocks atop them, humanity has been fascinated with columns and entablatures, whether they were known by that name or not, and the designs have continued to evolve.

#Vitruvius described five classes of temples, designated as follows: "#pycnostyle, with the columns close together; #systyle, with the intercolumniations a little wider; #diastyle, more open still; #araeostyle, farther apart than they ought to be; #eustyle, with the intervals apportioned just right." So, what does it mean to have "intervals apportioned just right?"

Aside from the subjective aesthetic criteria mentioned in https://pixelfed.social/p/Splines/802974815166948953, such as avoiding columns that "look thin and mean" and shafts that "look swollen and ungraceful," there were practical considerations, such as the gap being too wide to support heavy stone entablatures.

There was also the practical matter with intercolumniation that was noo narrow. "When the [temple] matrons mount the steps for public prayer…, they cannot pass through [narrow] intercolumniations with their arms about one another, but must form single file; then again, the effect of the folding doors is thrust out of sight by the crowding of the columns, and likewise the statues are thrown into shadow; the narrow space interferes also with walks round the temple."

So, intercolumniations of 2 column diameters (4µ) or less, as in #pycnostyle and #systyle, were considered too narrow. Likewise 3 column diameters (6µ) or more, as in #diastyle and #araeostyle, were too wide. The consensus sweet spot 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).

The image shows this variable intercolumniation.

Floor Plan of https://pixelfed.social/p/Splines/802974815166948953 showing #intercolumniation.

Greek architects classified temples and public buildings based on number of columns in front, number of columns in both front and rear, as well as interior columns.

The simplest buildings are those with walls on three sides, and partial walls called #antae (singular #antis) in front, flanked by just two columns.

Buildings with 2 columns in front are #distyle, 4 columns are #tetrastyle, 6 are #sexastyle, 8 #octastyle, 10 #decastyle, and those with 12 columns would be #dodecastyle.

The classifications are refined further. Those with 2 columns flanked by antae are called #inAntis. These never have any columns in the back or sides.

Tetrastyle buildings with 4 columns only in the front are #prostyle, and those with 4 columns in both front and back are #amphiProstyle.

Sexastyle buildings like those in the previous post are called #peripteral.

Octastyle buildings with densely arranged internal rows are called #dipteral, and when some internal columns are removed, the sparse structure is called #pseudoDipteral.

Decastyle buildings are also called #hypaethral. With 10 columns in front and rear, these are noteworthy for their width. In fact, they are so wide that they don't have a roof in the middle, which is open to the sky. Only the four sides have roofs supported by columns.

In addition to the number columns, there is a further classification based on #intercolumniation. #Vitruvius described five classes of temples, designated as follows: "#pycnostyle, with the columns close together; #systyle, with the intercolumniations a little wider; #diastyle, more open still; #araeostyle, farther apart than they ought to be; #eustyle, with the intervals apportioned just right."

The building in my previous post (shown without walls) has 6 columns in front and back — so, it is sexastyle. It is also known as a "Peripteral Eustyle," with column "intervals apportioned just right."