Treasures such as the Tara Brooch and the Lindisfarne Gospels, the earliest 'Celtic' crosses, and Anglo-Saxon poems belong to the 'Insular' tradition of art, evolved in ireland and England, seventh through tenth centuries.

What unites these superb creations is a shared method of designing: their forms are all generated as a coherent 'accumulated geometry.' With the simple tools of compass and straight-edge, and with profound understanding or proportion, the craftsmen created forms having perfect coherence and seamless resolution.

This site offers a practical guide to the designing of Insular art, in a combination of description of its tools and techniques and selected demonstrations of the creation of specific designs.

~ Robert D. Stevick

Descriptions

Tools

Only two tools are required, the compass and the straight-edge. They work on a flat surface (a plane).

Compass, also called a pair of compasses: Mechanically, this is nothing more than two members, usually called 'legs,' joined by a pivot, or hinge. The legs may be straight or curved or otherwise, so long as they are rigid. The joining may be at the ends of the legs, or at some point midway along their lengths. If midway, the compasses may be 'proportional,' the extensions at one end proportional to the extensions at the others.

Functionally, the compass is used for drawing circles or parts of circles ('arc'), and to 'take' measures. In drawing circles or portions of them, the end of one leg (its 'foot') is fixed in place, and the other end (the other 'foot') moves along a plane surface, marking its path. In taking measures, the feet of the compass are placed at the points to be measured.

Straight-edge: Mechanically, this is nothing more than a piece of flat material having one edge that is straight, that is to say, extending uniformly in a single direction.

Functionally, a straight-edge guides the path for a moving point for making the direct (shortest) path between two points.

Configurations

The four common configurations pair up to a large extent with the materials and the contexts of the artifacts.

• Circle: Typically brooches and bosses in metalwork have survived.
• Ringed Cross: Stone sculptures or carvings most commonly survive, but the form is appropriate to bookart as well.
• Rectangle: Illuminated 'carpet' pages in books are many; boxes made for book-shrines are few; the shape possibly is used in building design as well.
• Lineal Extension: Narrative texts in verse are divided into sections of unequal and non-modular length (unlike 'stanzas').

Three of these—circle, ringed cross, and rectangle—are configurations constructed on a plane surface (two-dimensional). All three can be seen. The configuration of segmented lineal extensions (one-dimensional) cannot be seen, even if the segmentations themselves are a conspicuous visual part of the text; it can be recognized only in the relations among the counts of metrical lines in the segments.

All four configurations depend for their creation or their development on setting lines at right angles. That is obvious in the rectangle forms and the crosses (ringed and otherwise). In the circular designs and lineal extension plans it may not appear in structural lines: but it always appears in the sources of the ratios among the lengths and the distancing of the principal lines.

Ratios

The ratios which govern the finest Insular designs incorporate integers 1 and 2 together with 'geometric' measures produced with 1 and 2 in right-angle configurations - √2, √3, √5

How these ratios are set up in Insular designing is the key to understanding the coherence of the designs. They are described and illustrated in detail with the Guide.

Guide

Here in old-fashioned print format is a practical guide to the Coherent Geometry of Insular Art. Sections 3 and 4 - Setting the Ratios, and Creating the Designs - are essentially demonstrations. Sections 1, 2, and 5 give some background to understanding the nature of Insular designing.

Demonstrations

Tara Brooch (QuickTime)

Dunadd Motif-piece (QuickTime)

Design Method Demonstration for Lunula (QuickTime)

Guthlac A, Commodular Relations Among the Parts (QuickTime)

More Information

Bibliography