Desmond Paul Henry, no. 634, Untitled, 1962, blue and red coloured biro on white paper, size: 49x53cm. Hand embellishments: pastel-pink background shading and black in-fills. Picture executed using Drawing Machine One, created by the artist from an adapted Bombsight analogue computer.

Picture 634 illustrates well Henry's modus operandi with regards to his generative art.

This picture was executed using Henry’s first drawing machine of 1961. This machine’s drawing potential centred around the rotational movement of a drawing arm interacting with a moving drawing table which together create a multitude of ellipses and Lissajous curves varying widely both in form and density and in regularity and irregularity. With this machine Henry was able to create the structures and shapes that form the basis of his complex, abstract machine drawings which he often deliberately left untitled, so the viewer could make their own imaginative response. While Henry had overall control of his imprecise drawing machines, he could not be certain of the effect of any mechanical adjustments he made, either before or during the execution of an artwork, meaning the end result would always contain the surprise element of unpredictability.

In picture 634 we can see that Henry has created a complex series of curved shapes based around ellipses flowing into each other and overlapping in a way that they seem to generate further three- dimensional forms, suggestive perhaps of some kind of mythical, bird-like creature. There is a great sense of fluidity and movement, as we seem to enter different planes and perspectives. The circular shape at the top draws us in as though we are entering a tunnel. On the way we meet spirals and curved tubes giving us other paths to follow; one taking us down to the bottom half of the drawing where we are trapped in a vortex. This is just but one journey we can take, as each tine we look at the work we can see new relationships between the different interlocking forms.

What is described here might seem quite chaotic, anarchic even, but there is also a sense that the whole is highly structured.

In a 1999 letter to his daughter, Elaine, Henry stated that in the composition of his drawings he focussed on "proportion, disposition, equilibrium and harmony" and we can see this in this work. The different elements are carefully placed, "disposed", to create a coherent entity. The artist has emphasised the outer contours of the machine- drawn structure that is at the centre of the work, with the use of thickened lines. He has even smoothed the outer edges by filling in spaces with black ink. On the left he has joined rounded edges with a thick black line and has created a hand drawn space like a flying buttress to support the angular shape above it. Within the lower section, a sort of rectangle with rounded corners at the base, there is a sense of a circular movement in the lower left half which counterbalances the round form at the top of the drawing. The darkened sections in the top and bottom halves of the central image, where the colour seems to change with the intensity of overlapping ellipses, echo each other. The "flying buttress" seems to link with the black infill to its right, while also being counterbalanced by a hollowed black shape towards the top right.

Another element Henry introduced is pink pastel-like shading. At the top it creates a curved backdrop, adding to the sense of depth. This shading flows in and out of the main structure helping to hold it together but also creating new rhythms as it interacts with the machine drawn curves.

In this drawing, therefore we can see the complex, symbiotic, relationship between Henry the artist, and the machine he built to give expression to his creative vision.
He plans and sets up the machine to work within certain parameters, makes further adjustments in response to its own act of creation, decides when this process is complete and unifies what has been formed, by adding further embellishments by hand. In this way we are left with a complete work that fuses design and chance, the mechanical and the human, in a harmonious expression of Man's imagination and technical ingenuity.