The Evolution of Useful Things: How Everyday Artifacts-From Forks and Pins to Paper Clips and Zippers-Came to Be as They Are.

by Henry Petroski

  The device of these inventors owes its novelty principally to a little hill, or a “camming protuberance,” that juts up from the can top. To open the can, the tab is rotated onto this hill, thus lifting up one end. This action not only pushes the other end of the tab into the scored can opening, thus breaking the seal and beginning the opening, but also lifts the end of the tab sufficiently above the top of the can so that even the stiffest and stubbiest of fingers can get a hold to complete the opening procedure. Closing the opened can is effected by peeling a protective covering off the now exposed bottom of the tab, revealing an adhesive underside that can be folded down, rotated into place, and wedged over the opening by the action of the hill. This procedure takes five figures to explain in the patent, and thus may appear to be as complicated as other resealing schemes. But if the resealing aspect were discarded, a beverage can with something like a “camming protuberance” could be a beautiful sight for sore hands.

  Independent inventors will no doubt continue to come up with ingenious schemes to respond to objections to current mechanisms for opening cans, but the companies that make and fill the cans will no doubt continue to focus their attention on their prime objective of preserving the contents in the most effective and competitive way. Of late, technical questions relating to the pros and cons of the availability, formability, and printability of steel versus aluminum have tended to dominate design and use decisions that ultimately have affected the form of beverage cans, and considerations of ultimate convenience and usability to the consumer have tended to be crowded out of the corporate if not the inventor’s mind.

  Since consumers tend to adapt to the pop tops that are generally available, there is often no business immediacy in exploring or introducing improvements. However, if such improvements would give one brand of beverage an advertising or marketing advantage over its competitors, that would be a change worth considering. On the other hand, there can also be a competitive risk in introducing an innovation that might prove to be too radical a change in form or function, and therefore be eschewed by the public. But, finally, if environmentalist or consumer concerns can be articulated as some kind of failure, as were those about removable pop tops, then there is a clear incentive for manufacturers to look at the end use of their products and containers as well as the immediate objectives of preserving and distributing them to people who must ultimately consume and dispose of them. Although a manufacturer’s concerns may sometimes appear arcane or selfish to the consumer, they are in fact no less driven by failure, whether functional or fiscal, than is any other aspect of the design, codesign, and redesign processes through which the forms of even our most familiar artifacts evolve.

  12

  Big Bucks from Small Change

  More than twenty-three hundred years ago, a series of “mechanical problems” and their solutions was compiled. Though classicists frequently attribute the collection to the Peripatetic School rather than to Aristotle himself, the Mechanica is usually grouped with the minor works of the famous philosopher but given scant scholarly attention. However, the thirty-five questions of the work show the considerable interest in engineering matters that was current in ancient Greece, as it must be in any civilization that wishes to function with some semblance of physical achievement, comfort, convenience, reliability, and economy. Indeed, the opening sentence of the Mechanica shows that the concept of engineering was essentially no different in Aristotle’s time from what it is today. While Aristotle began his introduction with the recognition that “remarkable things occur in accordance with nature, the cause of which is unknown,” he immediately conceded that “others occur contrary to nature, which are produced by skill for the benefit of mankind.” The skill of which Aristotle wrote is what has come to be known as engineering, whose formal definition in the 1828 charter of the British Institution of Civil Engineers was meant to encompass all but military endeavors:

  Civil Engineering is the art of directing the great Sources of Power in Nature for the use and convenience of man.…

  This definition so remarkably echoed the words of the Mechanica that it underscores the fact that, whatever it has been called over the centuries, engineering has been a timeless pursuit of all civilizations. Indeed, the official definition currently employed by the American Society of Civil Engineers reiterates the continuity of purpose:

  Civil engineering is the profession in which a knowledge of the mathematical and physical sciences gained by study, experience, and practice is applied with judgement to develop ways to utilize, economically, the materials and forces of nature for the progressive well-being of mankind in creating, improving and protecting the environment, in providing facilities for community living, industry and transportation, and in providing structures for the use of mankind.

  Though the society may be accused of trying to cover all bases with this definition, the roots in Aristotle’s notion of using “skill for the benefit of mankind” are unmistakable. And even if, in the turbulent wake of the Industrial Revolution, the engineering profession has fragmented into specialties, the idea of using natural resources and exploiting physical phenomena, whether or not perfectly understood, for the ends of civilization remains the foremost objective of all engineering, whether preceded by civil, electrical, mechanical, or other societal but not essential modifiers. Yet, no matter how it is qualified, no ancient or modern engineering is without economic considerations, which affect greatly the form of artifacts.

  Among the questions asked in the Mechanica is one of special relevance in a consideration of form in engineered things. It is question 25, and it reads:

  Why do they make beds with the length double the ends, the former being six feet or a little more and the latter three? And why do they not cord them diagonally?

  The first part of the question is given short shrift with a “probably they are of those dimensions, that they may fit ordinary bodies.” If they had failed to fit, the proportions of single beds would naturally have evolved to the happy medium where they did. But it is really the second part of the question that points to much more interesting and subtle aspects of how forms evolve. Aristotle’s answer is as follows:

  They do not cord them diagonally, but from side to side, that the timbers may be less strained; for these are most easily split when they are cleft in a natural direction, and they suffer most strain when pulled in this way. Moreover, since the ropes have to bear the weight, they will be much less strained if the weight is put on the ropes stretched crosswise than diagonally. Also, in this way less rope is expended.

  The parts of this answer dealing with strained timbers and ropes are really just assertions, for Aristotle does not elaborate on what is quoted here. This is consistent with the contemporary analytical understanding of forces acting at angles, which had still to be properly articulated. However, as has been the case throughout history, craft and engineering advances could and often did proceed even in the absence of scientific explanations. Certainly it required no theory of beds to invent the concept of a wooden frame drilled with holes through which a rope could be threaded to form a mattress support. The idea was known almost three thousand years ago to Homer, for in The Odyssey Ulysses describes, on his return to a skeptical Penelope, how he made the frame of their bridal bed out of the parts of an olive tree and in it drilled holes through which he threaded leather straps. The bed was unique in being anchored in the roots of the olive tree itself, and in holding a sentimental significance for the long-suffering couple. To them, the bed was inviolable. Knowledge of its origin was proof of Ulysses’s identity.

  More conventional beds, created not by ancient superheroes but by traditional craftsmen, would not have been so unchangeable. The cost, comfort, reliability, and maintenance of the common bed could easily have guided its evolution: if the timbers or the ropes sagged too much or broke, they would be pulled tighter or made heavier. The method of stringing thongs or ropes to form the bed would have evolved in response to questions of efficiency and
efficacy, with the craftsman reacting especially to correct weaknesses that brought beds to be repaired or drove customers to rival craftsmen whose beds did not need repair. But, whatever the comparative merits of crosswise and diagonal stringing patterns, what is clear from the Mechanica is that economy of material, and labor, was as much an issue in ancient times as it is now. Given that the basic form of the bed is as rooted in ancient craft tradition as Ulysses’s olive-wood specimen was rooted in the ground, there can be little doubt that the initial and upkeep costs of artifacts have always been strong determinants in their evolution.

  In a recent article on American rope beds, which have survived in use into the present century, two alternate methods of cording them also are discussed. In the one, the rope is threaded through holes, as described by Aristotle; in the other, the rope passes over pegs; but in both methods the ropes load the wood across the grain and so any tendency to split is minimized. Whatever method was used, however, the rope could be expected to slacken with time, and so special bed wrenches were kept handy to tighten it. This process would no doubt have caused bed ropes to break now and then, most likely just as someone was ready for a good night’s sleep on a nice firm bed. At times like that, a pegged bed would have been a godsend, since a broken rope could easily be knotted and threaded over the pegs in ways that it could never be through holes.

  How bed-cording patterns evolved in response to the failure of alternative patterns to be economical (of either material or time) is but another example of how failure influences the evolution of artifacts generally, and the forces at work both to drive and to hinder their evolution are most evident in the most common of objects. Thus, the displacement of steel by aluminum as the metal beverage container of choice has been tied to, more than any other factor, the economics of mills, those small fractions of a cent that are saved when each can is made a fraction of a mil thinner in a mill that is producing more than a million a day.

  There are countless examples of mass-produced products whose form has been altered to greater or lesser, better or worse degrees because of the demonstrated or perceived economics of changing materials or the processes by which they are altered or assembled. Design and redesign are always comparative activities, with choices necessarily being made to take this over that, these over those, and the choice is generally made in favor of the design that least fails to meet whatever collection of criteria the decision-makers employ. This may be less evident in the case of larger engineering structures or systems, where evolution often takes place on the drawing board and out of public view. In the last century, for example, when the railroads were being extended across the country, there was a continual need for laying out long sections of track over an ever-changing terrain. The route chosen through the wilderness not only determined the gradients up which locomotives would have to pull but also the number of waterways and valleys that would have to be bridged. This in turn affected the way in which the railroad altered the natural landscape. The characteristic forms of American as opposed to continental railroads—their different gradients, and the use of wood rather than iron in bridges—resulted from the different philosophies of their railroad engineers. The importance of the decision of where to locate a railroad was put in a concise context by A. M. Wellington in his classic Art of Railway Location:

  It would be well if engineering were less generally thought of, and even defined, as the art of constructing. In a certain important sense it is rather the art of not constructing: or, to define it rudely, but not inaptly, it is the art of doing well with one dollar, which any bungler can do with two after a fashion.

  Two schemes were popular for installing rope in Early American beds. In one scheme, the rope was passed through holes in the frame; in another, the rope was passed over pegs. Though there was little difference in the amount of rope used, the two schemes differed in the amount of time required to complete the process. Questions of economy and efficiency have always influenced the nature of engineering designs and the form of artifacts. (photo credit 12.1)

  Whether it be an ancient bed strung with less rope, a beverage can made with integral sides and bottom, or a railroad routed to avoid the need for a bridge, the question of economy of materials and energy provides a relatively objective comparison of alternative designs and is central to engineering and to all design. But, whereas the length of rope not used, the thickness of metal not required, or the number of bridges not built may be easy savings to calculate, such bean counting is not what distinguishes an artist from a bungler. Rather, the idea of economy in good design must involve questions of final benefit, not only for the capitalist but also for mankind.

  The bottom line is certainly of concern, both to those seeking profit and to those seeking value, but neither of these can be measured solely by the amount of dollars spent on production or product. The nonquantitative word “quality” conveys countless ways in which a more expensive thing might be more profitable and yet a better buy as well. The advantages of thicker metal in an automobile body can clearly be argued from various points of view, including resistance to denting and even simple snob appeal. Whereas the manufacturer can use these as selling points and also as justification for a higher price tag, the buyer can easily justify spending more for a car that will keep its appearance longer and provide a status symbol.

  Even when two virtually identical products are available at different prices, it is rare that price will be the sole criterion for choice. Consider the case of food in supermarkets. It is evident that the same product is priced differently in different stores, but not all products are more expensive at store A than at store B. Ideally, someone making shopping decisions based purely on price would compare the prices of each and every item on a shopping list and choose one from store A and another from store B, according to which is the better buy. This is essentially what supermarkets do in reverse (drawing up the shopping list after designing the register tape) when they advertise that a bag of groceries at their store saves the shopper so many dollars and cents over the identical bagful at another store. The advertising claim may certainly be true for the specific selection of items in the bag, but the savings might be reversed with another shopping list. Doing such detailed comparison shopping is obviously time-consuming, and would take the individual shopper at least three trips to two stores to accomplish. The time investment may be worth it to the store manager who uses it as an advertising gimmick over the competition, but how much is the shopper’s time worth?

  In rare instances, in the days before computerized pricing, different boxes of the same product were sometimes found priced differently on a store’s shelf, perhaps because the stockperson neglected to put new higher-price stickers over the ones on the older merchandise, or because the store manager chose not to include subsequent price increases on stock bought at lower wholesale prices. All other things being equal, the consumer would have been foolish not to select a lower-priced box, but all things are seldom equal. Aside from the question of freshness, older packaging may not be as attractive as the newer, and older packaging may not have the same convenient features as newer. Which box the shopper will select depends upon a complex set of criteria that differ from person to person precisely because we all have different priorities with regard to what we consider important (and ultimately economical), and the manufacturer or distributor of consumer products not only can play on this fact but must do so to remain competitive. It is not just capitalism that works on this principle; even in countries where there are long lines for indistinguishable products, the shopper makes a choice whether to stand in this line or that.

  The dynamics of food shopping is but a paradigm for making choices among artifacts generally, and although price can often be a major consideration in choosing one box or brand over another, it is seldom the only one. All we need do is browse among the supermarket shelves and read the claims of their “new, improved” stock. Whether one is attempting to sell a new brand of soap to a consumer or an invention
to a patent examiner, comparisons with the prior art are central to the case. A new product that is in every way identical to the old except in price is rare, for offering something at a lower price means that somehow it incorporates new materials or ingredients or processes the old in a more efficient way. Speeding up a production line may be a cost saver only if the money saved in production does not have to be spent on advertising to sell the additional output. The demand for some products does become so strong that new plants must be built and advertising hardly seems necessary, but with new plants often (though not always) come new (improved) processes using new materials. Who can remember a wildly successful mass-produced item that maintained all the identical qualities that launched its success? Subsequent versions tend to incorporate features that overcome prior faults or else, when driven by ill-advised economies, introduce new ones.

  Inventors may all dream that in the not-too-distant future a new factory will be required to keep up with the demand for their new gadget, but when they are in the early stages of seeking a patent their thoughts are often on past competition. The inventor Nathan Edelson lives in Montana and has worked on designs combining computer work stations with exercise equipment. In the course of describing a trip to the Patent Office in Washington to do his own background checking of what had been done along the lines of his idea for an adjustable or “active” desk, he related his joy at finding that, although there were plenty of precursors to his idea, his invention did have a competitive advantage:

  Ideally in a patent search, you hope to find “prior art” that attempts to accomplish the same “objects” as your invention, but which, for one reason or another, fails to do so adequately. This generally indicates that the potential benefits of your invention are recognized as legitimate, but that the means for achieving them need significant refinement or rethinking.