In the patent literature, the term "prior art" is virtually synonymous with "state of the art," the standard against which any claimed improvement is necessarily judged. Normally, "state of the art" implies the latest technology, and thus, what's considered the prior art tends to change over time.
There is a category of devices in which this seemingly self-evident fact does not hold true.
The paper clip is one of the simplest of useful things. In its most familiar embodiment, it's formed by making three bends in a four-inch length of wire to produce what has been described as a loop within a loop. Architects and product designers often place this inexpensive little object on top-10 lists of iconic designs, by which they mean things that have a certain aesthetic cachet.
To engineers, design depends more on function than on form. Whereas an architect or product designer may tend to hold in his or her mind an image of the paper clip as a pristine, silvery, metallic object photographed against a contrasting dark background, an engineer is more likely to imagine the thing in the functional context of holding together a sheaf of papers. In that configuration, it's not so much an object of aesthetic beauty than of functional cleverness.
The classic loop-within-a-loop paper clip is known as the Gem, after the late 19th-century stationery firm Gem Ltd., which first made and sold it. Because no patent was taken out on the innovative clip, other manufacturers of office products soon copied, marketed, and sold it.
But, as engineers and designers well know, no design is perfect. The Gem clip was known to have a number of shortcomings. In particular, its rough wire ends tend to scratch and tear paper. As a result, as early as the end of the 19th century, inventors began to come up with clever modifications for which patents were issued for improved functionality.
But if no design is perfect, then it follows that no derivative design is perfect. For every advantage embodied in a new paper clip design, there appeared to be an equal and opposite disadvantage. For example, one common solution to the problem of a wire end tearing paper was to form the end into a very tight eye. This certainly did work, but at a price: The tighter bending radius demanded the use of steel that was more resistant to cracking, which meant a more expensive raw material.
Thus, the Gem, for all of its real and perceived faults, remained the state of the art, and so the prior art against which all challengers were judged. This was true at the beginning of the 20th century, and it remained true at the beginning of the 21st, as hundreds of patents for improved paper clips attest. In other words, the Gem still represents a happy medium of design.
In part because it has held its exalted technological position for over a century, the Gem has become a challenge that many an inventor -- amateur and professional alike -- has taken up. The simplicity of the device entices inventors into thinking they can do what no one before them has done: Displace the Gem from its position of superiority in technological elegance, product design, and market share.
When these dreamers are not turning over a Gem in their fingers, contemplating its pluses and minuses, these proposers of new paper clips are devisers of medical devices, manufacturers of automotive wire products, and designers of office chairs. They have all shared the same ambition: To succeed where countless inventors before them have failed.