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Home , Magic lantern, Movie projector, Overhead projector, Projector, Slide projector, Slide show

A reprint from American Scientist the magazine of Sigma Xi, The Scientific Research Society

This reprint is provided for personal and noncommercial use. For any other use, please send a request to Permissions, American Scientist, P.O. Box 13975, Research Triangle Park, NC, 27709, U.S.A., or by electronic mail to [email protected]. ©Sigma Xi, The Scientific Research Society and other rightsholders Engineering

Next Slide, Please

Henry Petroski

n the course of preparing lectures years—against strong opposition from Ibased on the material in my books As the some in the artistic community—that and columns, I developed during the simple projection devices were used by closing decades of the 20th century a the masters to trace in near exactness good-sized library of 35-millimeter Carousel begins its intricate images, including portraits, that slides. These show structures large and the free hand could not do with fidelity. small, ranging from bridges and build- slide into history, ings to pencils and paperclips. As re- The cently as about five years ago, when I it joins a series of The most immediate antecedent of the indicated to a host that I would need modern slide was the magic the use of a projector during a talk, just previous devices used lantern, a device that might be thought about everyone understood that to mean of as a obscura in reverse. Instead a -mm (or its to add images to talks of squeezing a life-size image through a equivalent), and just about every venue pinhole to produce an inverted minia- had one readily available. Nowadays, ture, the magic lantern employed when I say I will be showing slides and to project through a system an en- will need a projector, just about everyone ry of the cave, in which prisoners could largement of an image painted on a glass assumes that I will employ a PowerPoint view only shadows cast on the wall that slide. The device’s origins are as fuzzy presentation, and that what I need is a they were constrained to view, can be as its first images must have been, but digital projector. Indeed, the conversion taken as a paradigm of the captive audi- primitive magic lanterns were employed from physical to digital “slides” has been ence. In Plato’s cave, the source of illu- as early as the 15th or 16th century. so rapid and complete that the Eastman mination was a simple fire strategically , whose Magiae Kodak Company ceased manufacturing placed behind a bridge that served as a Naturalis first appeared in the mid-16th its classic late last year and has stage over which actors crossed to cast century, described the process of using let it be known that it cannot guarantee the shadows that became the extent of a convex lens to focus the projected im- that parts or service will remain available the prisoners’ external reality. ages of transparent drawings. Further- after 2011. Thus, the once-ubiquitous 35- Natural phenomena also provided more, “To these drawings he attached mm slide projector will soon become a precursors to controlled projection. A movable parts, and thus produced as- museum piece. rainbow is just the sunlight behind us tonishing effects, which the unlearned refracted into its component by ascribed to magic, a term connected with Obligatory Obsolescence the spherical of raindrops. The the lantern ever since.” (In the mid-19th and its artifacts are always right natural conditions can also result century, when the magic lantern would being superseded, and the demise of the in the phenomenon of pinhole projec- reach a high level of sophistication, one Kodak slide projector signals the begin- tion, as when rays cross as they lecturer would wish “that some more ning of the end of yet another chapter in pass through the chinks in tree cover scientific, if not so familiar, a name for the long history of using images to sup- to cast on the ground an image of the our instrument were recognised.”) plement words. Arguably, the earliest sun. Viewers of solar eclipses exploit the As is typical of a new technology, illustrated lecture was in effect a game same phenomenon, employing a pierced incremental improvements were soon of charades, with ideas communicated card, to view the celestial drama indi- made, and by the 17th century the de- through gestures. Hand shadows added rectly, so as not to endanger the human vice had been developed sufficiently illusion and broadened the repertory of eye. The (a “dark cham- to be employed in scientific lectures to the hands themselves. Prehistoric cave ber” fitted with a small through project microscopic and other images. painting may have been but an early which light can throw an outside im- Among scientists who were instrumen- means of illustrating lectures about bat- age onto an opposite wall), known at tal in such endeavors were Johannes tle and hunting strategies. Plato’s allego- least since ancient times, domesticated Kepler and Christiaan , who is the natural phenomenon and captured sometimes identified as the inventor of Henry Petroski is the Aleksandar S. Vesic Professor images of landscapes that artists could the modern magic lantern. The typical of Civil Engineering and a professor of history at trace. The contemporary artist David lantern of the time consisted of a cham- Duke University. Address: Box 90287, Durham, Hockney, joined later by the optical sci- ber that contained a light source, such NC 27708-0287 entist Charles Falco, has argued in recent as an oil lamp, whose heat and fumes

© 2005 Sigma Xi, The Scientific Research Society. Reproduction 400 American Scientist, Volume 93 with permission only. Contact [email protected]. were dispersed through a chimney. The “.” Image diameters of the or- ing such slides at Wellesley College dur- light was directed through a - der of 60 feet dwarfed the lecturer, who ing the 1953–54 academic year.) like cylinder, which by the end of the often stood on the stage and used an had been intro- 17th century typically held, in receding enormous wooden pointer to direct the duced in the mid-1930s, making pos- order from the light source, a condens- gaze of thousands of eyes to a detail. sible the 35-mm “ transparency” ing lens, a fixture by means of which By the end of the 19th century, magic slide. This was a lighter, more compact glass slides could be slid in and out of lanterns had in their own right become (2-inch square) and shatterproof alter- the light path, and a native to the 3-1/4-inch moveable lens square British and the 3- for focus. The size of the 1/4-by-4-inch American image was controlled glass lantern slide, but it by the distance of the was also a more expen- lantern from the surface sive one. Still, some art on which it was to be historians insisted that projected. the smaller slides simply The use of the in- did not provide as sharp strument for popular an image as glass lantern entertainment grew in slides, and so they, like the the late 18th century, Wellesley instructor, con- when it began to be tinued to use the old but employed to produce arguably superior technol- shows known as phan- ogy. With the introduction tasmagoria (literally, “a of Kodachrome II film and gathering of ghosts”). To then the Kodak Carousel maximize its effective- projector in 1961, howev- ness, the phantasmago- er, the days of the magic ria lantern was often a lantern and its glass slides lightweight model made were numbered. of tin painted black and with a crooked chimney. Projecting Overhead These features enabled Not all lectures or presen- the handheld lantern tations require high-qual- to be moved about a ity photographic slides. totally darkened room Especially for situations without being readily that relied more on pic- seen, whereby the pro- tures as diagrams and jected ghostly images freehand sketches, the appeared to hover and development of the over- move by themselves. By V&A Images/ head projector provided the middle of the 19th The magic lantern was developed in the 15th or 16th century and evolved con- a quick and easy alterna- century, magic lantern siderably over subsequent centuries. This one was made in Germany in the tive to slides. An early 19th century. shows of all kinds had version of the overhead become popular sources of education, objects of beauty and complexity, fash- projector (in the form of a reconfigured edification and entertainment to which ioned out of brass and glass that shined magic lantern) existed around the turn admission was charged. The develop- and glittered. At the same time, a new of the 20th century, but more modern ment of led to the print- technology began to be introduced, that ones date from the mid-1940s, when ing of photographic images directly onto of the motion picture, which would re- they were introduced as an aid in po- glass plates, which when sandwiched place the public lecture as a means of lice work. They soon found their way together with a second glass plate bound mass entertainment. At first, magic lan- into bowling alleys and schools, where to the first produced durable slides. Itin- terns continued to be used in conjunction they were used to project scores and erant lecturers, who traveled with their with the , to show titles lessons as they were written down in magic lanterns the way magicians do and advertisements while reels were be- real time. Soon, even tradition-bound with their bag of tricks, became as popu- ing changed. Soon, however, the magic scientists and engineers who eschewed lar as their lectures. lantern was relegated primarily to scien- slides as a medium too rigidly set in Improvements in the light source and tific and academic purposes. As late as glass or celluloid for their extempora- optics enabled increasingly brighter, the middle of the 20th century, it was still neous presentations began to embrace sharper and larger images to be shown, being used for lectures in such fields as the use of the , at which meant that larger and larger audi- art history and medicine, areas in which first using rolls of clear film stretched ences could be accommodated. Among large libraries of high-quality glass lan- over the projector’s stage and eventu- the most common means of illumination tern slides had been accumulated over ally employing 8-1/2- by 11-inch sepa- was to direct jets of oxygen and hydro- a long period of time. (The art-history rate transparencies. After all, the pro- gen to mix in flame on a stick of lime teacher in the movie Mona Lisa Smile was cess of drawing on plastic film was not (calcium hydroxide) and thus produce shown, apparently quite accurately, us- so radically different from writing on

© 2005 Sigma Xi, The Scientific Research Society. Reproduction www.americanscientist.org 2005 September–October 401 with permission only. Contact [email protected]. the blackboard. Besides, it allowed the hard-copy output of the pe- screen to verify what slide was being writing to be done on a more natural riod, the slides still had to be picked up shown. Were it not for the fact that 35- horizontal surface, and colored pens at a central computing facility, where mm slides—like lantern slides before could be used to highlight and clarify the relatively costly hardware resided. them—were so inconvenient to create, points of discussion. There were other problems with store, carry and arrange, they might Handwritten notes and hand-drawn slides and slide projectors. Like the have remained the medium of choice charts were generally considered too in- overhead, the slide projector was typi- for presentations of all kinds. formal to project at serious management cally placed directly in front of the meetings, for which attendees dressed screen. However, since it was not as PowerPoint 1.0 up in suits and ties. So the overhead bulky and could be fitted with a remote With the widespread arrival of the per- projector did not come into widespread control so the presenter did not have to sonal computer in the early 1980s, the use for business presentations until the stand immediately beside it, the good technical groundwork was laid for a mid-1970s, when the Xerox machine be- seats were not necessarily preempted— new alternative, one addressing the came a familiar office appliance. Then, as long as those sitting in them could theretofore accepted limitations and finished-looking transparencies (also hear the lecturer over the cooling-fan failings of the 35-mm slide and its cum- known as “overheads” or, in some indus- motor. Depending on the limitations of bersome infrastructure. Assigning ab- tries, “foils”) could be made from neatly the available lenses, the slide projector solute credit for the development of a typed and drawn material, and anything might have to be closer or farther from computer application, like any inven- that could be photocopied—including the screen to get the desired image size. tion, can be difficult, since ideas tend to , pages of books, computer The start of many a presentation was be in the air and feed off one another. printouts, and charts and graphs—could delayed while an extension cord was Someone may suggest the germ of an thus be projected onto a screen. tracked down, or a book or other object idea, but another person might carry it However, like any other technology, of the right height was located to serve to fruition. The problem is not unique the overhead projector is not without its to prop the projector up at a suitable to . Samuel F. B. Morse en- limitations. It is bulky and usually sits angle. (Many users forgot, ignored or gaged in long and acrimonious debate on an even bulkier table or cart directly never knew that the projector had ad- and legal wrangling with Dr. Charles in front of the screen. The presenter usu- justable feet.) A compromise often had Jackson, a physician-geologist from ally has to stand beside it to have easy to be reached between projecting the Boston who claimed that the concept access to the stack of transparencies that image high on the screen and minimiz- for the telegraph was their “mutual dis- is usually placed on the table to one ing undesirable keystoning. covery,” made in 1832 while they were side of the overhead projector, with a In America, in the latter part of the both crossing the Atlantic aboard the space on the other side of it frequently 20th century, the most popular slide ship Sully. being reserved for piling up the trans- projector was the Kodak Carousel. In 1981, Whitfield Diffie, a mathema- parencies after they are displayed. (All Like any consumer product, it came tician and cryptography expert, was too often, one of the piles is in the path in a variety of models (designs), and it working on problems relating to tele- of the stream of air emanating from the evolved over the years through incre- phone-system security at Bell-Northern cooling fan, which can shuffle the trans- mental improvements that removed Research Laboratory. By his own ac- parencies into disorder.) The projector the little (and big) annoyances of oper- count, in the course of preparing to put itself and the presenter standing beside ation that frustrated early users. These together a 35-mm slide presentation, it block the view from what otherwise included bulbs blowing, slides melting Diffie wrote a computer program that might be considered the most desirable and mechanisms sticking. Neverthe- could draw a frame on a sheet of paper. seats in the room. less, by the 1980s, at least, the machine He subsequently augmented his pro- had developed into a “perfected” and gram to draw a number of such frames The Carousel of Time highly reliable device that was largely on the same sheet and to allow text to The preferred alternative long re- user-friendly and trouble-free. be included inside them. The result was mained, of course, 35-mm slides. How- In spite of all the potential pitfalls, the layout for a “,” which ever, in order to create a set of slides a well-prepared and -executed slide could be given to a graphics depart- and thus a slide presentation, the imag- presentation in a well-equipped au- ment, which in turn could return to Dif- es first had to be collected or prepared, ditorium could be a thing of beauty. fie a finished set of 35-mm slides for then they had to be photographed un- In such a case, the slide projector was his presentation. Arguably, this was the der proper lighting conditions with a most likely enclosed in a projection germ of the idea for developing com- 35-mm camera, and then the film had booth in the back of the room, more puter software that could produce a to be developed before being cut into or less at the same height as the large slide show that would also run on—and frames to be mounted into slide frames. screen in the front, thus eliminating off—the computer, thus eliminating the Typically, in an organizational or insti- the problems of noise, keystoning and need for the physical slides altogether. tutional setting, a professional graphics head shadows. The speaker stood at Diffie has been reported to have said department did most of the work, and a lectern beneath or to one side of the it was a colleague, Bob Gaskins, who a certain lead time had to be allowed. screen and had a remote control that appreciated the value of such an appli- This began to change with the introduc- was either hardwired to or in cation and who “was the one who had tion of the computer, and by the mid- to or contact with the projector. The the vision to understand how impor- late 1970s computer graphics software speaker could be fitted with a lapel tant it was to the world.” made it possible to compose slides on a microphone, so that her voice was not According to Ian Parker, who inter- terminal’s screen. However, like much lost when she turned to look at the viewed both Diffie and Gaskins for a

© 2005 Sigma Xi, The Scientific Research Society. Reproduction 402 American Scientist, Volume 93 with permission only. Contact [email protected]. using 35-mm slides and a PowerPoint presentation became increasingly easy to make. Anyone but the most hide- bound traditionalist or computer-pho- bic individual preparing a new lecture is likely to do so on a computer, sav- ing the digital file on a hard drive or a compact disk. My own new talks are composed entirely on my laptop and illustrated exclusively in digital format. I still occasionally do carry a loaded carousel with me on a trip, but only be- cause I have been asked to give an older talk, whose (still undigitized) slides are the kind that require an old-style pro- jector to operate. But I can no longer assume that when I say I will need a projector for my talk that it will be understood to be a 35-mm slide projector that I require. Even if this is understood, I increasingly expect that I may have to set it up myself. Many a young student assigned to operate the PowerPoint presentations have all but replaced slides and overheads, but not always to good highly sophisticated digital equipment effect. Here we see a slide from computer scientist Peter Norvig’s parody, “Gettysburg Ad- dress,” prepared using the Autocontent Wizard. (Image courtesy of Peter Norvig.) in a modern projection booth has never even seen, much less operated, a Kodak New Yorker article on PowerPoint pre- to film slides in color and resolution.” Carousel. More and more, I find myself sentations, Gaskins observed others in Among their greatest advantage was instructing the student in how to set up the laboratory using ill-suited computer that the “slide is ready as soon as it is the old analog machine. Soon, I may equipment to make overhead trans- designed.” Now, of course, PowerPoint have to carry extra bulbs along with parencies and got the idea to design a is as generic a product name as Kleenex my own carousel, for it is unlikely that graphics program that could create and and Xerox. a suitable spare will be found among edit virtual slides. In 1984, he left Bell- When PowerPoint was still a relative the electronic devices. Indeed, it is more Northern to join Forethought, a strug- novelty, audiences were surprisingly likely than not that as their bulbs blow, gling Silicon Valley software company. patient with the “new technology,” the old 35-mm slide projectors will be rele- Gaskins and Dennis Austin, a software unelaborated-upon term that was mut- gated to the equipment closet for which developer, began working on a pro- tered frequently before, during and af- no one holds the key. gram they called Presenter, which to ter a speaker introduction that could not avoid a trademark problem was to be be stretched out any further. With the Acknowledgment renamed PowerPoint before first going speaker fully introduced but the slide This essay draws on material from the first on sale in 1987. PowerPoint 1.0 was a show not yet ready, everyone just stood of three Louis Clark Vanuxem lectures that black-and-white Macintosh application around or sat and watched in silence I presented at Princeton University on De- that enabled users to print out pages as the new technology was coaxed out cember 7–9, 2004. A book based on the that could be photocopied onto over- of its black box. As recently as the late lectures will be published in the spring by head transparency film. Soon, Microsoft 1990s, meetings could be stopped dead Princeton University Press. acquired Forethought and with it Pow- for 20 minutes while technicians, speak- Selected Bibliography erPoint. The first version of PowerPoint ers and well-intenders huddled over Bolton, H. C. 1891. Notes on the history of the for Windows came out in 1990, and the a recalcitrant laptop computer trying magic lantern. Scientific American 64:227. much-maligned Autocontent Wizard (a to project onto an auditorium screen Gage, Simon Henry, and Henry Phelps name suggestive of the system’s magic- a PowerPoint presentation. Such inci- Gage. 1914. Optic Projection: Principles, lantern roots), which ostensibly helps dents led many a one to be backed up Installations and Use of the Magic Lantern, the user create a presentation, was add- with overhead transparencies or 35-mm Projection , Reflecting Lantern, Moving Picture Machine. Ithaca, N.Y.: ed in the mid-1990s. At about the same slides, which continued to be carried to Comstock Publishing. time, the production of 35-mm film meetings by some presenters. Now, of Hockney, David. 2001. Secret Knowledge: slides began to level off and decline. By course, laptops of all makes and models Rediscovering the Lost Techniques of the Old the late 1990s, PowerPoint was avail- interface easily with a similarly diverse Masters. New York: Viking Studio. able in 35 languages, and accounted assortment of projectors, and inserting Hope, Tom. 1998. Presentation Slides: Electronic for an increasing number of slides of all a CD into a strange laptop and calling and Film. Rochester, N.Y.: Hope Reports. kinds and as many as 70 percent of the up its contents usually—but still not Parker, Ian. 2001. Absolute PowerPoint. The nearly two billion “professional elec- always—goes off like clockwork. New Yorker, May 28, pp. 76. Robinson, David, Stephen Herbert and tronic slides” made worldwide annual- With the development of more user- Richard Crangle, eds. 2001. Encyclopaedia of ly. The growth continued, even though friendly, more compact and less ex- the Magic Lantern. London: Magic Lantern early electronic slides were “inferior pensive projectors, the choice between Society.

© 2005 Sigma Xi, The Scientific Research Society. Reproduction www.americanscientist.org 2005 September–October 403 with permission only. Contact [email protected].