simple well-known four struts X-module architecture series

The X-module

Probably the first tensegrity ever..

Professor Amy C. Edmondson wrote a book about Buckminster Fuller which is called A Fuller Explanation. The book is very easy-reading and educating at the same time. It is full of geometry of course, because Fuller was filled with geometry, but she also tries to explain the person "Bucky" in which she dares to be critical as well. Her Preface starts with: "Buckminster Fuller has been alternately hailed as the most innovative thinker of our time and dismissed as an incomprehensible maverick, but there is a consistent thread running through all the wildly disparate reactions. One point about which there is little disagreement is the difficulty of understanding Bucky. "It was great! What did he say?" is the oft-repeated joke, describing the reaction of a typical enraptured listener after one of Fuller's lectures."

The book is a great effort in explaining Fuller's Synergetics, but unfortunately the part in which the tensegrity is described is not very clear. Here, all sentences she spent on describing the "birth" of the first tensegrity:"In the summers of 1947 and 1948, Fuller taught at Black Mountain College, and spoke constantly of "tensional integrity". Universe seems to rely on continuous tension to embrace islanded compression elements, he mused; we must find a way to model this structural principle. Much to his delight, a student and later well-kown sculptor, Kenneth Snelson, provided the answer. He presented his discovery to Fuller: a small stucture consisting of three separated struts held rigidly in place with a few strings."

It is probably the worst part of the entire book. Not only did she spend to few words on an episode so important to Bucky, nearly everything is wrong. For instance, the period was not 1947 and 1948 but 1948 and 1949 and more important, Kenneth Snelson did not make the simplest 3-prism tensegrity which she described by "a small stucture consisting of three separated struts held rigidly in place with a few strings." Instead he made the X-module shown here at the right.
Let it be clear that I don't want to bring Mrs Edmondson's work down. The reason I give it this much attention is because I think it is exemplary for the mist that hangs over this first tensegrity and the distorted relation between Snelson and Fuller. But let's start at the beginning.
After serving the Navy during the last years of World War II, Kenneth Snelson entered the University of Oregon in Eugene in 1945. In an interview with Richard WhelanSnelson recalls:"My brother advised going into business, because then you can do anything. I studied accounting and called it pre-law. Then there was a teacher giving a terrific Shakespeare course, so I switched to an English major. After that I became interested in architecture and architectural drawing, and from there I got into design. There were quite a few painting students in the design class, so through them I was gradually drawn into painting... ...It had never occurred to me that someone from Pendleton, Oregon, could be a painter. I had always thought that you had to be touched by God or something. And, of course, when I announced at home that I was going to be a painter, the first question was: 'How are you going to make a living?'... ...After two years at the University of Oregon, I realized that the G.I. Bill would pay for me to study anywhere. I was interested in the Bauhaus and had read about Albers and seen pictures of his work, so I applied to Black Mountain College for the summer session of 1948."

Whelan's detailed article on this subject continues: "That was the summer when everybody-including Willem de Kooning, John Cage, Merce Cunningham, Richard Lippold and Buckminster Fuller-showed up at Black Mountain. For Snelson the decisive influence of that crucial summer turned out to be not Albers but Fuller. Inspired by Fuller's gospel of structure and technology, Snelson decided he didn't want to be a painter after all."

It is clear from this article that Snelson was greatly inspired by Fuller. In a letter to R. MotroSnelson writes about this episode: "Buckminster Fuller, unknown to most of us in those early days, turned up two weeks into the session, a substitute for a professor of architecture who canceled a week before the summer began. Josef Albers asked me to assist the new faculty member in assembling his assortment of geometric models for his evening lecture to the college. There was no such thing as a tensegrity or discontinuous compression structure in his collection, only an early, great circle, version of his geodesic dome. Albers picked me to help because I had shown special ability in his three-dimensional design class.
During his lecture that evening Professor Fuller mesmerized us all with his ranging futurist ideas. As the summer quickly went by with most of the small school monitoring Fuller's classes I began to think I should try something three-dimensional rather than painting. Albers counseled me that I demonstrated talent for sculpture. But, more importantly, I had already become the first in a trail of students from colleges and universities who, over the years, were to become electrified "Fullerites". He had that cult-master's kind of charisma. I blush for it now, but it was true. We were young and looking for great issues and he claimed to encompass them all."

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Fuller and Snelson in 1949

Then, in the same article, Snelson tells us how he came to the X-piece: "At the end of the summer session, I returned home to Pendleton, Oregon. In my Fullerian trance the descent into the real world was greatly confusing. I spent the autumn at home, making my parents miserable by moping and spending hours in the basement, building things; small mobile sculptures mostly, using thread, wire, clay, metal from tin cans, cardboard, etc. I had learned much about geometry from Fuller as well as art and design from the Bauhaus. While Albers' teachings were imparted as useable ideas in public-domain, Bucky's lessons were laden somehow with the sense that the ideas were proprietary -- "his" geometry. I believed, literally, because he claimed so, that before Buckminster Fuller came along, no human had ever noticed, for example, that to inscribe the diagonals of the square faces of a cube was to define two interlocking tetrahedra within. Students joked that, after all, hadn't Bucky invented the triangle? None of us knew, for example, of Alexander Graham Bell's early space frames, nor anything at all about crystallography.
In the autumn of 1948, as I said, I made numbers of small studies. Were they structures or sculptures? They incorporated the attitudes of both Fuller and Albers... ...One step leading to the next, I saw that I could make the structure even more mysterious by tying off the movement altogether, replacing the clay weights with additional tension lines to stabilize the modules one to another, which I did, making "X", kite-like modules out of plywood. Thus, while forfeiting mobility, I managed to gain something even more exotic, solid elements fixed in space, one-to-another, held together only by tension members. I was quite amazed at what I had done.."

You can still hear some admiration for Fuller, but now scepticism takes over and it got worse. There is a lot to read about Kenneth criticizing Fuller the way he stole his idea but at this stage I think the following citation of Kenneth about his X-module in an interview with Angela Schneider will do:"This little discovery which I made in Pendleton, Oregon at 114 N.W. 8th Street in the winter of 1948-49 was the beginning of what you see today at the Nationalgalerie. Next summer at Black Mountain, I first showed this magical structure to my teacher, Buckminster Fuller. He was both amazed and delighted. As a student, I was also delighted that he was amazed. Life had not yet prepared me for the possibility that he would publish it as his own work, which he did. This was 28 years ago, but numbers of people are under the impression still, that Fuller originated this structure, which, of course he did not."

A lot of quarrelling went on but at this point in history the situation was as follows: On one hand, there was Kenneth Snelson, a twenty-two year old student who had tried several courses, but hadn't found "the right track" yet. On the other hand, there was "Bucky", a charismatic and inspiring teacher with fresh ideas and stimulating sessions. Snelson admired him at that time and for sure it helped him being creative..

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Two pieces, both made by Kenneth Snelson

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The "X-piece" made by Kenneth Snelson in the winter of 1948

I am not an art conaisseur who can elaborate about the development of the painting technique of a famous painter like Rembrandt or Picasso. My field of experience is tensegrity, but I don't think this X-piece tells you much about the development of the construction technique of the sculptor Kenneth Snelson.
But I do think that this piece shows us in different ways how difficult it is to invent a simple three strut tensegrity prism.
First, there is the use of X-formed compression parts. I don't think that, at that time, Snelson could imagine you could build a space consuming construction with just sticks and strings. Not only for Snelson, but probably for everyone it was already amazing that you could pile up material just by using strings. One should realize that the complexity of a tensegrity lies in it's simplicity. So, using simple struts instead of complex X-forms was just a bridge too far.
Second, there are all these strings and not all of them seem to be that important. This is interesting because tensegrity constructions are the best constructions to demonstrate the separation and the coöperation of tension and compression. In this X-piexe the seperation is not entirely clear. It looks like Snelson searched for a plain sculpture but used more than he needed, being afraid that when he left everything out there would be nothing left to show.
Finally the bottom of the sculpture. I think the primal stage of the tensegrity is best expressed by this wooden floor. One of the typical characteristics of a tensegrity is that it is a structure that is not dependend on the force of gravity. And this one isn't eather, but Kenneth, living in a world that had build structures that did depend on gravity for thousand of years could not throw it all away at once.

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Just for fun I removed half the picture at the top of this page just top concentrate on the "tensegrity heart" of the structure.

The small study above was commented on by Kenneth with the following words: "I think your discussion of the X-module is fine."

Personal note
After this X-piece, many different tensegrities were build by many people throughout the world but nearly all of them use simple sticks or struts. It looks like the complex X-form was just a small station in the road of the tensegrity development. But I still think there is a large field of possibilities wide open and I hope for a revival of beautiful tensegrities made with "complex" compression parts. To be honest, I made a small start which can be seen on steel bows and wooden rings.

When we say that the X-piece is the first tensegrity ever built, then it is ligitimate to ask ourselves if this X-piece meets with the definition of a tensegrity. Whatever the answer, one should realize that the word "tensegrity" didn't exist until "Bucky" Fuller invented it five years later. I'm afraid the answer depends on the definition that is used. For instance the definition of R. Motro says: "Tensegrity system is a system in a stable self-equilibrated state comprising a discontinuous set of compressed components inside a continuum of tensioned components." It sounds difficult but the key-word here is "inside". With this word R. Motro (among many colleagues) likes to distinguish "real" tensegrities from "bicycle wheel" structures. At first it looks like both X-forms are inside the tendons, but as shown in the picture that shows the heart of the tensegrity, most tendons are "fake" and the real tensegrity-part of the structure is just half the X-piece. Within that tensegrity-part the compression elements are not really inside the tension components but more at the surface of the construction. So, according to this definition the first tensegrity is no tensegrity at all.

But what if we use the definition of Kenneth Snelson himself? In that case we let him decide wether he made a tensegrity or not.
In an e-mail to Valentín Gómez Jáuregui, Kenneth wrote in August 2004: "... the other domes you cite can not be considered tensegrity, regardless what people wish to call them. They are, essentially, bicycle wheels. Did the world need a different name for that kind of solid rim, exsoskeletal structure? I think not; same with a spider web. I've made this point in my writings which you probabaly have come accross in your research. Yes Fuller declared that everything in the universe was tensegrity. Tensegrity structures are endoskeletal prestressed structures -- and that restriction leaves out endless numbers of items. As I've said also elswhere, if everything is tensegrity then tensegrity is nothing of any particular sort; so what's the point in using that word?"
So according to Snelson himself you could not call this X-module a tensegrity, at least, it is hard to call this structure "endoskeletal". The irony is of course that according to Fuller it is a tensegrity.
In a personal e-mail to me dated august 16, 2009, Kenneth describes it even more clearly: "In regard to a definition at your website please note that in order for non-touching compression members to be suspended in a network of tension they must reside on the inside of that prestressed network. Thus, with the bones inside and the muscles inside, we have an endoskeletal structure. This endoskeleton principle is a unique property of tensegrity structures which are different from carousels, bicycle wheels or spider webs -- which are exoskeletal. These do not fit a proper tensegrity definition since each of these depends on an external compression ring or outer framework to support the internal tension lines; an important distinction when one seeks to define the word "tensegrity". By now, a quite impossible task in any case." One can not state that the X-module is endoskeletal and therefor it is hard to say, according to Snelson himself that he had made the first tensegrity.
Of course I have discussed this theory with Snelson and this was his reply (complete e-mail): "Dear Marcelo, I can see I ought not to have gotten into a micro examination of definitions with you since it takes a lot more time than I have to give to it.
What you say is in a hair-splitting sense partially true. Yes, one can argue that six of the outside tendons are "fake" but they're not actually fake in this structure since they counter the inward pull of the sling members that support the two X modules at the crossings. Without the outside tendons the joint in the middle would be greatly stressed. The six "fake" tendons counteract those forces.
As you say the "tensegrity" theme didn't exist when I made that structure but that's beside the point. The important point is that this was a pioneering work for structures capable of filling all space when inter-suspended by tension members; a space-filling structure extendable ad infinitum by continuing to add modules at each quadrant. See the two pieces below. This was a profound aspect of what got to be called tensegrity. But really Marcelo I had no wish, when starting out, for semantic nit-picking arguments about definitions; but I did. There are too many opportunities to split hairs. To the extent I've split hairs with you I apologize.
I admire your intelligence and your building skills which is the reason I've taken the time to respond as thoroughly as possible to your thoughtful questions. I'm too old and too short of time to once again tear apart the history of tensegrity for further refinements."

See the photos at the left for the pictures he mentioned in his e-mail.

Finally I have to mention Snelsons reaction when I showed him my first wooden rings. This was before I confronted him with the theory the X-module might not be a tensegrity: "No, I have never seen a structure like the one on your tensegriteit site. Hard to define it it's endoskeletal or exoskeletal. Maybe it's both at the same time."

The borders of "outside" and "inside" don't seem to be so sharp as they used to be.

I think in the end we shouldn't be to specific about the definition because when he made his X-module, Kenneth took a giant step in the development of the tensegrity.
Besides the X-module can be called "floating compression" structure for sure. And "floating compression" is the word combination that was invented by Kenneth himself, which shows once more that he knew exactly what he had invented.

Small sculptures made by Kenneth Snelson

It is clear that Snelson has some experience with bended compression elements, but when one looks at his entire artistic career one must conclude that his heart goes to the simple straight tubes.

Normally one needs at least three struts to make a tensegrity, but here, several examples show that with bended struts, or complex compression elements one only needs two. This is because a straight strut has only one dimensione (a line) where a complex compression element has two (a surface).

kenneth snelson 01 series "curved tube sculptures", made by Kenneth Snelson
Marcelo Pars