impossible trident

This outrageous piece of draftsmanship evidently escaped from the Finagle & Diddle Engineering works. If the contributor of this item—sent anonymously for some reason—will identify himself, we will happily pay $10 (ten bucks) or a two-year subscription to Analog . It’s impossible to publish even a small fraction of the letters that outrageous piece of draftsmanship evoked. There were well over one hundred fifty letters on that one item alone—and while we have long been aware of the unusually high level of intelligence of Analog ’s readership, the high level of honesty was a new and pleasant discovery. Not one of all those letters claimed to be the original contributor, or demanded the ten dollars! Campbell added that readers had directed his attention to other instances of the illusion, which he said was sometimes called a “blivit” [sic], in recent issues of such publications as Road & Track , QST , The SAE Journal , “various and sundry house organs,” and textbooks on topology and psychology. And in December, he printed a letter from Edward G. Robles, Jr. of Sacramento, California, who claimed that the image had originated at the Jet Propulsion Laboratory in Pasadena. The invention of the blivet has been convincingly attributed to the Swedish graphic artist Oscar Reutersvärd, the originator of many other impossible figures, who asserted in a letter quoted in Bruno Ernst’s The Eye Beguiled that he had drawn “figures of the devil’s fork type” in Stockholm in the thirties. For its explosion in popularity in the sixties, however, we can look a little closer to home. In the October issue of Analog that I mentioned above, Campbell printed a letter from James E. Tunnell of Industrial Camera, based in Oakland, California, which featured a blivet on its company letterhead. Tunnell wrote: While a student in grade school some twenty years ago, I saw for the very first time, in my old red mathematics book, a drawing much as that shown in the upper-left hand corner of this letter, and very much like that in your publication. In the field of higher mathematics, this model is known as a Two-Slot, Mark 4, Blivit—origin unknown—and during the past ten years has gotten into the hands of many organizations through our business dealings with them . For reasons that I’ll explain in a moment, the italics are mine. And I’ll just note for now that it’s only half an hour by car from Oakland to Belmont, where California Technical Industries was based.