It is often told that in the 1860s, John Henry Pepper used science and technology to invent a ghost.
Or did he?
This is the surprisingly tricky question that we will try to answer in this lengthy post.
It is a somewhat sad and recurring theme in science that many discoveries are not named after the actual people that discovered them. In fact, this phenomenon is so common that it has a name — Stigler’s law. Appropriately, Stigler’s law was, in fact, first discovered by Robert Merton.
This effect is not necessarily the result of deception or injustice. The history of science is complicated, and it so happens that things are often “discovered” multiple times before their significance is truly appreciated and recorded by the scientific community. One example is Snell’s Law, which describes how the direction of light changes when it crosses the boundary between two different transparent materials. Named for Willebrord Snellius who observed it in 1621, it was noted by English astronomer Thomas Harriot twenty years before, and in fact had been first discovered by Persian mathematician Ibn Sahl in 984.
In the case of “Pepper’s ghost,” the issue is weighing the relative contributions of two discoverers who each made important contributions. There are in fact two key inventors whose roles must be examined: John Henry Pepper (1821-1900) and Henry Dircks (1806-1873). Their story inextricably entwines science, engineering, legal theory, and entertainment.
But what is “Pepper’s ghost”? Our definition will change as this post continues, but we begin with the depiction of it as given in Wikipedia. It is an optical illusion that presents to an audience the appearance of a three-dimensional transparent figure — a ghost — in a room.
The illusion is created by a piece of glass stretched across the visible stage, and the ghost is in fact another person, brightly lit, in a hidden stage. The reflection of the ghost figure off of the glass makes it appear as if it is on the visible stage, and with careful planning it can appear to interact with actors on that stage. Because the reflection is a reflection of an actual three-dimensional figure, the illusion is itself three-dimensional and can be extremely convincing.
Pepper’s ghost is still used to this day. In 2012, it was used to create a virtual Tupac Shakur to perform alongside Snoop Dogg at Coachella; folks widely and mistakenly referred to it as a “hologram.”
Pepper’s ghost is also employed in the Haunted Mansion at the various Disney theme parks; I’ve blogged about it in this context a number of years ago. In the mansion, ghosts appear and disappear as they cavort around a massive dining hall.
We will discuss both of these illusions in more detail near the end of the post; for now, we turn to how the ghost was invented and the craziness that followed.
I will draw from a variety of sources to tell the story, but there are two main sources that I simply must describe right now: the separate memoirs of Pepper and Dircks themselves! I came across both of them serendipitiously on the internet some years ago. Pepper’s is titled The True History of Pepper’s Ghost, and was published in 1890, almost 30 years after the invention. And it has the most amazing cover!
Dirck’s own book came out in 1863, a year after the ghost was invented, and its short title is The Ghost! Its long title is The Ghost! as produced in the Spectre Drama, popularly illustrating the Marvelous Optical Illusions obtained by the apparatus called the Dircksian Phantasmagoria: being a full account of its history, construction, and various adaptations. Regardless of the wordiness of the title, Dirck’s book also has a really excellent cover.
Our story begins with Henry Dircks, English inventor and scientist. Born in 1806 in Liverpool, he started his adult career as an apprentice in a mercantile firm, though he spent his free time reading. Not only did he study chemistry and mechanics (the physics of motion), but he also had an interest in literature. In the 1820s, be began lecturing on science as well as publishing scientific and literary articles in local magazines. He had a passion for science education, which would play a role in his motivation for introducing “the ghost,” as well. He worked as an engineer, and was active in both literary and scientific societies throughout his life. He wrote a dozen books, in science, engineering, biography, history and poetry, and took out numerous patents during his lifetime.
We give you all these details to give an image of Dircks as not only a highly creative man of both science and art but one who really seems to have viewed those disciplines as a higher calling for the betterment of humanity.
The “ghost,” like so many discoveries, was made by Dircks accidentally, sometime around 1858. As he himself describes,
It is more than twenty years since I first invented a plane mirror of unsilvered glass, but finding no practical utility in the contrivance, it was laid aside. It happened, however, that within the last two years I accidentally observed a solid body in a peculiar situation, by which it was apparently rendered transparent. It was, in short, an effect illustrated by my plain unsilvered glass mirror in its principle. I immediately saw that, by means of this combination, the singular appearance could be produced of getting behind a mirror and communicating with its shadows. Here, then, a means was at once at hand for producing the best possible illustrations of all descriptions of spectral phenomena.
This description came from Dircks’ original presentation of his invention to the British Association in September of 1858. A printed version appeared in numerous publications that same year which included crude drawings of how Dircks’ envisioned his illusion might be performed on stage; he later included a better drawing for his book The Ghost!, as shown below.
In short: K is the plate of glass, and H is the place from which an audience would observe the show. J is a location for letting light in to illuminate the regular stage, where I is a location for illuminating the hidden stage. With that hidden stage at L illuminated, the figure Y would form a ghostly image at Y’, and with careful orchestration this figure can interact with regular actors Z on stage.
The same year the Dircks introduced his invention, he advertised it in newspapers and showed it off to a number of theaters and scientific organizations in the hopes of finding someone to implement it on a large scale. He found no takers, however, and one can readily imagine why. Dircks’ illusion requires sunlight to be visible, which would force theaters to hold performances only during daytime. Even worse, Dircks’ scheme would require a hidden stage be built underneath the audience, a prohibitively costly reconstruction for most venues.
Several years passed before Dircks attempted to sell his invention again; in the meantime, he had occupied himself with travel and other projects. When he made the second effort, he would find an interested party in John Henry Pepper.
Pepper was another British scientist and inventor, born in 1821 in Westminster, London. While in school, Pepper became interested in chemistry and quickly mastered the subject, becoming an assistant lecturer at the Grainer School of Medicine by age 19. In 1847, at age 26, he presented a lecture at the Royal Polytechnic Institution, an institute of science and higher learning, and the success of that led to him being appointed as the director of the institution within a few years.
One of the places that Dircks brought his invention was to the Royal Polytechnic, and here we let Pepper explain what happened, from his True History:
The Christmas of 1862 was fast approaching, when Messrs. Horne, Thornthwaite, and Wood, philosophical instrument makers, of Newgate Street, invited the author to see a model which Mr. Dircks had caused to be constructed. This was the beginning of the Ghost; but as Mr. Dircks said that an entirely new theatre must be built to show the effects which he allowed could only be seen by a few people placed in an upper gallery, and then only by daylight, it was no wonder that the Crystal Palace, the Colosseum, and other places had all declined to have anything to do with Mr. Dircks or his model, which was now placed in the hands of Professor Pepper…
Note the rather irritable tone of Pepper in this narrative, which foreshadows trouble to come!
Pepper made two significant changes to Dircks’ original idea. The most obvious was to replace sunlight by electric lighting, allowing the illumination to come from anywhere. The more significant change can be explained through the use of Pepper’s own diagram, shown below.
The key to the effect is the small area below the stage on the lower right of the figure; we zoom in below.
The “ghost” leans back upon the platform k; he is illuminated by an electric light c, which can be rapidly blocked by the shutter b1. The image is reflected off of an inclined pane of glass f, which presents the illusion of the ghost on stage.
Though Pepper’s scheme allowed for the ghost to be readily displayed in any theater, there are several limitations compared to Dircks’ approach. Because the ghost figure must be inclined, it cannot walk freely around the stage; Pepper put the entire lower stage on rails b in order for the ghost to at least move across the stage. Also because the ghost is tilted, its image will be tilted, giving it an odd appearance on stage. Dircks himself, in his memoir, sniffs somewhat derisively at Pepper’s modifications, saying that the original scheme had been set up with “much curtailment.”
Nevertheless, Pepper’s version of the ghost wowed anyone who saw it. He first demonstrated it on Christmas Eve to a select audience; in his words:
Just before Christmas Day in 1862, I invited a number of literary and scientific friends, and my always kind supporters, the members of the press, to a private view of the new illusion to be introduced into Bulwer’s romantic and dramatic literary creation, called ‘A Strange Story.’ The effect of the first appearance of the apparition on my illustrious audience was startling in the extreme, and far beyond anything I could have hoped for and expected, so much that, although I had originally settled to explain the whole modus operandi on that evening, I deferred doing so, and went the next day to Messrs. Carpmael, the patent agents, and took out a provisional patent for the ghost illusion, in the names, at my request, of Dircks and Pepper.
The “Bulwer” mentioned above is Edward Bulwer-Lytton (1803-1873), a quite innovative and successful novelist who is best remembered these days for being overly dramatic. If you’ve ever heard the opening line, “It was a dark and stormy night,” you’re familiar with Bulwer-Lytton: it came from his 1830 novel Paul Clifford. I’ve blogged about his historical romance The Last Days of Pompeii as well as his early science fiction novel The Coming Race, which is one of the earliest examples of the genre. A Strange Story is a supernatural mystery published the same year that “the ghost” was unveiled to the public: 1862.
Dircks and Pepper filed a joint patent on the invention on February 5, 1863, “Apparatus for exhibiting dramatic and other performances.” They furthermore came to an agreement by which displays of the ghost could continue at the Royal Polytechnic, and they were an instant smash hit. They were first shown in the smaller theater at the Polytechnic, but crowds grew so quickly that the show was moved to the larger theater by Easter of 1863.
The first official play done with “the ghost” as a star was an adaptation of Charles Dickens’ Christmas ghost story “The Haunted Man“, and they received permission from Dickens himself to do so! “The Haunted Man,” first published in 1848, is very much in line with Dickens’ first and most famous Christmas ghost story “A Christmas Carol” — in both tales, a wicked man is shown the error of his ways through the intervention of spirits.
The ghost became a genuine sensation throughout Britain, and beyond. Licensing agreements were made for other theaters performing different shows. For instance, a July 21, 1863 review of “The Patent Ghost” in The Mercury newspaper reports on the ghost almost as a living actor,
After having bowed to the public at the Polytechnic institution, he some weeks ago made his debut upon the boards of the Britannia Theater in a new and highly original drama, entitled, “The Widow and Orphans, — Faith, Hope, and Charity,” in which piece he continues to present himself nightly to crowded audiences with the highest imaginable success.
The ghost was a cultural phenomenon as well, even getting mention in the satirical newspaper Punch. A parody of a ghost play was given in the May 16, 1863, issue, of which I present only a small snippet:
[A Skeleton appears at the back of the Stage. Guilty Aristocrat defies Skeleton. Skeleton feebly defies Guilty Aristocrat.
Audience (immensely terrified). Brayvo! Go it! Give it ‘im. [Skeleton vanishes.
Guilty Baronet. Ha! Gone! [Skeleton reappears suddenly.
Audience (deeply impressed). Here we are again! [Great applause. Skeleton vanishes.
Guilty Baronet. Is it a Phantom of the Be-rrrain?
Mothers. Chicketty, chicketty, &c.
Ghost of Injured Victim (appearing). Ha! ha!
Guilty Baronet (who is taken by surprise). What do I see?
Discriminating Audience. Brayvo, Pep-per!
Guilty Baronet. My sword!
[Assaults the Spectre, who laughs demoniacally and vanishes, as the GUILTY BARONET falls flat on his face and the curtain descends amidst overwhelming applause.
The popularity of “the ghost” could have been predicted by anyone familiar with history. Some 65 years earlier, physicist and stage magician Étienne-Gaspard Robert stunned Paris audiences with his own ghost show, the Phantasmagoria, which today we would view as a clever take on a slide projector (“magic lantern”). Robert, known as “Robertson,” made a fortune with his shows, which I have blogged about in the past. Dircks was certainly aware of this himself, as he referred to his illusion as the “Dircksian phantasmagoria.”
Pepper and the Polytechnic Institution did very well with the ghost as their star; Pepper himself claims to have raised 12,000 pounds doing shows at the institution over a 15 month period. In 2016 dollars, this is estimated to be roughly $1.4 million — and Pepper notes that it did not include licensing fees from other theaters.
Dircks, curiously, did not see much, or even any, other this money. By his own statement, he was only interested in being giving public credit for his (fundamental) role in the invention:
Shortly afterwards, enquiry was made in a very straightforward manner as to what would be my terms in the way of commission. My terms not being pecuniary, but simply the connection of my name with my invention, there was no difficulty to be raised.
I am not sure why Dircks would have surrendered all financial rights to a project that was immediately and obviously going to be extremely lucrative. One possibility is that he simply felt that, as a man of higher learning, recognition of his efforts was reward enough. Dircks seems to have been independently wealthy at the time of his invention, and likely did not need the money anyway. There is another possibility, however, not mutually exclusive. We noted earlier that Dircks discovered the ghost when working with his own patented glass: he may have concluded that he would make all his money by selling glass for the illusion, rather than selling rights to the illusion itself.
Others, however, were very eager to get their hands on some of that sweet, sweet ghost illusion money. Unauthorized shows began to pop up, but Pepper was ruthless in enforcing his patent rights to crush them. One notice to this effect, reproduced by Pepper in his True History, appeared in the London New Music Hall Journal on August 10, 1863; an excerpt appears below.
It is with unfeigned regret that I have to announce to my numerous patrons the withdrawal of the Ghost from the London New Music Hall. The reason is as follows : — My engagement with Mr. King, to whom a large sum of money was paid down, was with the understanding that he should personally superintend the first representation of the “Great Optical Illusion, the Marvellous Ghost,” which, however, he failed to do, and to which is attributable the failure and disappointment which ensued. I also distinctly understood that his representation was free from any infringement of the right of patent, and that it was in every respect equal to the original production of Professor Pepper.
Since breaking the patent was not a successful strategy, entrepreneurs turned to another approach: suing to invalidate the patent entirely. This description, by Pepper, is so fascinating that it is worth reproducing in its entirety; those who find legal arguments boring can skip past the lengthy quoted section.
The famous ghost trial came on in September at the private residence of the Lord Chancellor Westbury, who very graciously agreed to hear this patent case at once, because his lordship was informed by my solicitor, Mr. Walter Hughes, junr., that if he could not do so the Polytecnhic Ghost would most likely be swamped by the multiplicity of imitators, good, bad, or indifferent.
Accordingly, one cold and chilly day I went down into Hampshire, accompanied only by my solicitor, Mr. Walter Hughes, junior, of the firm of Hughes, Masterman, and Hughes, 56, New Broad Street. On arrival we were shown into his Lordship’s drawing-room, where, to my dismay, I found a little army of solicitors and barristers drawn up as if in battle array, and sitting in a row against the right-hand wall of the room.
His Lordship’s secretary courteously came forward, and, noticing we were somewhat cold, placed chairs for us near the fire, and pulled up a table for our use on which to take notes.
We all rose respectfully when the Lord Chancellor entered, and, being requested by him to remain seated, the case was opened by his Lordship asking who appeared for the Plaintiffs, the music-hall proprietors. At least four answered, “I do, my Lord,” and we in the minority could only give an answer from one voice — viz., that of my then young solicitor.
The music-hall people came down with two newspaper reporters to record their certain victory over me, but which, as it turned out, was a mistake, because the reporters could only tell the truth and record the verdict given in my favour.
The Lord Chancellor, so far as I can remember (and I have no notes), then addressed the Plaintiffs —
1st. I shall require you to show cause by what right or authority you appear before me this day.
2nd. I will hear you on the general merits of the case.
3rd. And lastly, on the novelty which the Defendant seeks to have completed under the protection of a Patent, and which novelty you appear to deny.
One of the barristers then rose, and after saying that he would bow with submission to anything his Lordship might suggest or rule, commenced his argument by calling attention to the fact that the number of days allowed by the Patent Law had already elapsed, and by sections so-and-so I had lost the opportunity of getting the Patent sealed within the proper time allowed between granting Provisional Protection and sealing the Patent.
After he had ended, the Lord Chancellor asked if the Plaintiffs through their counsel had anything more to urge on this first point. They all bowed, and said “No.”
His Lordship now said : “It is very true what you state respecting the wording of the Patent Act, but if you will turn to sections so-and-so you will find that the Law Officers of the Crown have full power to grant an extension of the time for completing and sealing the Patent on the proper application of the Defendant’s solicitors, and as that application has already been made and granted, it must be evident that, though the Defendant exceeded the time usually allowed, he had full permission to do so from the constituted authorities. I will now hear you on the general merits of the case.”
Here the learned counsel exhausted his law and rhetoric in making out there was really nothing to patent, for who could catch hold of a ghost? And more legal technicalities were advanced and argued than I can remember at this distance of time — viz., twenty-six years ago. However, his Lordship again asked, “Have you anything more to urge on this point?” and received the same reply, “No, my Lord, we have not.” The Chancellor then replied in extenso, exposed all the sophistries of the arguments, and whilst complimenting the counsel on his learning and the care which he had bestowed upon the case, said again that there was nothing in the arguments that militated against the sealing of the Patent. Of course, they could take action at common law, and try the case before the judges appointed to try such cases if they though proper, and, supported by affidavits resulting from a trial at common law, could bring the case again before him.
There was one point which the Lord Chancellor alluded to. He said: “Great stress had been laid on the impossibility of patenting a mere intangible nothing, viz., a ghost; but as he understood, the Defendant did not patent the shadowy result called the Ghost, but an apparatus for `Exhibiting Dramatic and other Performances,’ and without this apparatus no ghost could be rendered visible to an audience.” His lordship then continued: “I will now hear you on the novelty of the proposed invention, which your affidavits declare is not new, but an imitation of something already exhibited.”
The learned counsel now made various statements, supported apparently by affidavits from persons who alleged that they had seen the ghost a long time before, and, in fact, had used the very same apparatus I had employed or words to that effect. For instance, an old playbill emanating from the Old Tivoli Gardens, Margate — not perhaps the most refined place of entertainment, in fact, no ladies appeared to visit the place say, in 1851, when I heard a lady in tights discourse a song the burthen of which was —
“Take care, John Bull, or else you’ll be done
In the Great Exhibition of ’51.”
The playbill was laid upon his Lordship’s table, who, taking hold of it, asked, “Is this the playbill alluded to?” and threw it on the floor. I suppose the counsel was not attending to some point of etiquette, and ought to have produced his playbill in the form of a High Chancery Court affidavit. The playbill alluded to a ghost that was to be shown, and counsel again called attention to their plan of the ghost apparatus, which he was instructed to say was the same or very similar to that used by Defendant. The affidavit of some other dramatic professional was also brought forward with several others; but all things come to an end, and at last the same distinct question rang out: “Have you anything more to urge on this question of novelty?” with the answer as before. “No, your Lordship.”
Lord Westbury commenced by alluding to the drawing brought forward by the Plaintiffs, and said, “I have examined the affidavit and the drawings and find it is nearly as possible a copy of the Defendant’s own drawing deposited in confidence in the archives of the Patent Office, and when I visit that establishment will take care to enquire who has presumed to allow the Plaintiffs permission to copy the Defendant’s original drawing of the apparatus used to show the ghost. I well remember,” continued his Lordship, “being taken to the house of Belzoni, the distinguished traveller, and seeing an effect no doubt somewhat similar to that produced by the Defendant’s apparatus, but I could not for one moment compare the toy of Belzoni with the refined and complete contrivances used by the Defendant at the Royal Polytechnic. An affidavit has been put in by the Plaintiffs, sworn to by a person calling himself a ‘nigger minstrel.’ He is elsewhere denominated an ‘Ethiopian Serenader,’ who had seen the Defendant’s ghost shown years ago — a very respectable man, no doubt, in his vocation; but to put the evidence of such a person against the affidavits of Michael Faraday, Sir David Brewster, and Professor Wheatstone, is a manifest absurdity. I, therefore, rule that the Great Seal of England be at once attached to the Defendant’s patent, and that the Plaintiffs do pay the costs.”
After certifying for the costs and having a little conversation with my solicitor and self, his Lordship withdrew, and we all went back to town. The reader can imagine my feelings of joy at the successful upshot of this trial when he learns that I had already received large sums for licenses which I must have refunded if the case had gone against me.
This story has almost everything in it — drama, twists, turns, legal shenanigans, and celebrity cameos! It also highlights the point we made at the beginning of the post, about “official” discoveries often not being the first discovery. Though his Lordship dismissed the claims that the ghost was already being used in the particular patent case before him, it is clear that others had stumbled upon similar illusions at earlier times, and just not achieved the same successes with them.
Speaking of due credit, the “famous ghost trial” was not the only legal issue involving the ghost to manifest near the end of 1863, and here we return to the original question of the name of the invention. As “the ghost” spread across the country, it became known as “Pepper’s Ghost” in all the theaters, to the great frustration of one Henry Dircks. Dircks found himself writing letters, often, to theaters and newspapers, correcting the record regarding his role in the invention. One example from the May 2, 1863 edition of The Athenaeum illustrates his irritation:
Allow me to state, with reference to the ghost scene now performing at the Britannia Theatre, that it is my invention which is there used, as adapted by Prof. Pepper for stage effect. My invention of an arrangement for producing certain optical illusions is calculated to supersede the magic lantern and all phantasmagorical and other apparatus hitherto employed; for whereas they only produce a motionless visionary figure, I associate on the same stage a phantom with a living actor, both different in costume, &c., and both acting in concert. Thus the scene may show them as sitting at the same table, on the same couch, opening the same cabinet, handling the same document, and, what is more, so seated in the same chair as to appear but one figure, yet seen one to arise out of the other, to go through different performances. The phantom character of one of such actors is shown by impregnability, passing through walls or furniture, or slow or quick dissolution. But effectually to fulfil these conditions would require a small building purposely designed for such performances, and therefore much credit is due to Prof. Pepper in having overcome the many obstacles presented by an ordinary stage.
These optical illusions are of a character calculated to disabuse the public mind in regard to the vulgar errors respecting apparitions, a belief in which has deprived many of reason; but which, as in this instance, may be realized by art, and, when occurring naturally, are mostly traceable to generally-known physical causes.
In the second paragraph, we see Dircks-the-noble-scientist again, pushing the ghost illusion as a way to educate the public against superstition. In the first paragraph, he is politely correcting the record regarding “Pepper’s ghost” — but it is only May! By the end of the year, he became convinced of more or less a conspiracy against him. Lawyers that Dircks approached did not know how to handle such a case, and he went into mediation with Pepper’s representatives to sort it out. Nevertheless, the misprepresentations continued, and this in fact motivated Dircks to publish his 1863 book The Ghost!, intended to clear the record. In the Preface, Dircks sounds genuinely paranoid about the situation:
Some philosophers will have it that “man is the creature of circumstances;” I know some to be the subjects of strange accidents, thus: — 1. My invention as first exhibited before a body of reporters, was accidentally reported without name. 2. For weeks together the handbills and placards of the Polytechnic accidentally omitted my name. 3. A letter was obtained from me as an authority to negotiate with Mr. Fechter, but it accidentally struck the possessor to have it legally stamped… [four more points of ‘accidents’ are listed by Dircks]
In fact, you will not find Pepper’s name anywhere in the main body of Dircks’ book: he omitted Pepper just as he imagined that Pepper had omitted him! Pepper, in his 1890 book, on the other hand, has no problem mentioning Dircks’ role often, and he seems genuinely offended at the accusations of chicanery. The two men never apparently reconciled, as the tone in Pepper’s book would suggest. Even without the acclaim of a ghost, however, Dircks did not suffer, career-wise: he continued to publish books, he was made a Fellow of the Royal Society of Edinburgh in 1867, and he received an honorary degree from Tusculum College in Tennessee in 1868.
Was there a scheme against Dircks in the naming of the illusion, or was there something more obvious and fundamental at work? I can’t discount the possibility that Pepper may have been working nefariously behind the scenes, but I would guess that the true explanation of how Dircks’ name disappeared has more to do with psychology. “Pepper’s ghost” has a, well, peppery ring to it: it sounds exciting! “Dircks’ ghost,” or “the Dircks-Pepper ghost,” does not. I really suspect that Dircks was undone by the simple fact that his co-inventor has a more interesting and catchy name than he does.
Dircks’ noble decline of royalties may have ironically worked against him, as well. The theater managers would have been sending their licensing payments to Pepper’s agents, and dealing directly with those agents; because Dircks had no financial interest in the affairs, he does not seem to have been involved in any negotiations. The managers of the various establishments would have almost naturally assumed that Pepper was the only inventor — what person with any legal claim would turn away the vast sums of money being offered?
Before we conclude our lengthy tale, we should share a few more of the many ironies to this story. Let us consider again now the modern implementations of “Pepper’s ghost,” particularly in the Haunted Mansion at the Disney parks. My illustration below shows, roughly, how the illusion is performed at the mansion.
The glass pane is oriented vertically, and the actual figures are located above and below the observers in the moving “doombuggy.” But this is exactly Dircks’ original plan for how the illusion should work! The most famous implementation of “Pepper’s ghost” in fact does not use the work of Pepper at all. For comparison, below is another illustration of Dircks’, showing how his illusion would be displayed in a theater.
The “hologram” of Tupac mentioned earlier is further removed from the ideas of Pepper and Dircks, as the image seen on the screen is only a projection of a recorded image, not a reflection of an actual three-dimensional figure (though I suspect that there is additional optical science involved, but that is a story for another day). “Tupac’s ghost” is only distantly related to the work of the 19th century pioneers.
One final irony is worth mentioning related to the origins of what I will, going forward, call the “Pepper-Dircks ghost,” and it comes from the words of Pepper himself.
During the time I was in Paris, and arranging the ghost for exhimition at the Theatre du Chatelet under Mons. Hostein, I was surprised to find that the conjuror, Mons. Robin, was showing the ghost at his seances. My lawyers interviewed him, and discovered that, some years before, a little toy had been brought out and patented in France by which a miniature ghost could be shown. It consisted of a box with a small sheet of glass, placed at an angle of forty-five degrees, and it reflected a concealed table, with plastic figures, the spectre of which appeared behind the glass, and which young people who possessed the toy invited their companions to take out of the box, when it melted away, as it were, in their hands and disappeared.
In a manner similar to that of Snell’s law that we discussed at the beginning of the post, it turns out that the Dircks-Pepper illusion had been implemented on a small scale years earlier by some nameless inventor whose name is lost to history. The Wikipedia picture of “Pepper’s ghost,” shown again below, is closer to this anonymous illusionist’s work than to Dircks’ or Pepper’s.
In giving credit to any scientist or inventor, therefore, we should keep in mind that there are often nameless geniuses who came before them, “ghosts” of their own sort!
Thank you. This was wonderful.