In the 1932 book Houdini and Conan Doyle (Bernard M L Erst & Hereward Carrington) an unsolved mystery is described:
Houdini produced what appeared to be an ordinary slate, some eighteen inches long by fifteen inches high. In two corners of this slate, holes had been bored, and through these holes wires had been passed. These wires were several feet in length, and hooks had been fastened to the other ends of the wires. The only other accessories were four small cork balls (about three-quarters of an inch in diameter), a large inkwell filled with white ink, and a table-spoon.
Houdini passed the slate to Sir Arthur for examination. He was then requested to suspend the slate in the middle of the room, by means of the wires and hooks, leaving it free to swing in space, several feet distant from anything. In order to eliminate the possibility of electrical connections of any kind, Sir Arthur was asked to fasten the hooks over anything in the room which would hold them. He hooked one over the edge of a picture-frame, and the other on a large book, on a shelf in Houdini’s library. The slate thus swung free in space, in the centre of the room, being supported by the two wires passing through the holes in its upper corners. The slate was inspected and cleaned.
Houdini now invited Sir Arthur to examine the four cork balls in the saucer. He was told to select any one he liked, and, to show that they were free from preparation, to cut it in two with his knife, thus verifying the fact that they were merely solid cork balls. This was accordingly done. Another ball was then selected, and, by means of the spoon, was placed in the white ink, where it was thoroughly stirred round and round, until its surface was equally coated with the liquid. It was then left in the ink to soak up as much liquid as possible. The remaining balls Sir Arthur took away with him for examination, at Houdini’s request.
At this point, Houdini turned to Sir Arthur, and said: “Have you a piece of paper in your pocket upon which you can write something?” The latter stated that he had, also a pencil. Houdini then said to him: “Sir Arthur, I want you to go out of the house, walk anywhere you like, as far as you like in any direction; then write a question or sentence on that piece of paper; put it back in your pocket and return to the house.” Sir Arthur walked three blocks and turned a corner before he wrote upon the paper - doing so in the palm of his hand. He then folded the paper, placed it in an inside pocket, and returned to Houdini’s home. Meanwhile, Houdini had kept Mr. Ernst with him in order to see that he did not leave the house.
Upon Sir Arthur’s return, Houdini requested him to stir up the cork ball once more in the white ink, and then to lift it, by means of the spoon, and hold it up against the suspended slate. He did so, and the cork ball stuck there, seemingly of its own volition! It then proceeded to roll across the surface of the slate, leaving a white track as it did so. As the ball rolled, it was seen to be spelling words. The words written on the slate were: “Mene, mene, tekel, upharsin.” The cork ball then dropped to the floor, and Houdini invited Sir Arthur to take it home with him, if he so desired. Sir Arthur extracted the piece of paper from his pocket, and upon it he had written, “Mene, mene, tekel, upharsin.” The message written upon the slate was therefore an exact copy of the message which Sir Arthur had written upon the paper.
Over the years several magicians have offered their solution to the mystery. These range from a person hidden behind the board using a long stick to manipulate a magnetised cork to Houdini performing Max Berol’s Menetekel illusion. The latter is in fact exactly same effect but performed on stage rather than at the close quarters desccribed in Houdini and Doyle. It’s believed that Houdini had bought this effect from Berol prior to his meeting with Doyle.
Not satisfied with any of these solutions Bob Loomis scoured the archives, gathered every piece of information he could and came up with his own solution which combines some elaborate information gathering and complex electronic equipment. You can read about it in his new book Houdini’s Final Incredible Secret which you can buy here.
I read the book. And instead of scouring the archives for years I did a search of Ask Alexander and my Kindle. So you might rightly consider my conclusions hastily drawn. However, something has always bugged me about this unsolved effect. And it’s probably that the only source of it seems to be the account given by Bernard Ernst to Hereward Carrington. Ernst was Houdini’s lawyer as well as an amateur magician. He later inherited the Houdini diaries which still remain with the Ernst family. Carrington was a magician and author of popular books on the supernatural. He had been at odds with Houdini over the investigation of the psychic Margery Crandon. He had also been the business manager of discredited psychic Eusapia Palladino. These two men are not the unbiased witnesses we’d hope for and Bob Loomis does note this in his book. It’s easy to imagine that Ernst wanted to portray his friend Houdini a great mystifier and Carrington wanted a good tale to tell. But that’s just guesswork and so is the rest of what I’m about to write.
I can’t offer any evidence that this miraculous trick with the inky cork ball did not occur. But I am sceptical that the account is correct. And if the account isn’t correct, then trying to find a solution that exactly matches the conditions is a lost cause. Here are the questions that lead me to believe that Ernst and Carrington’s tale has a touch of fantasy about it:
Why did Houdini make no mention that the trick was performed? The event was said to have happened between April 9th and June 23rd of 1922 when Arthur Conan Doyle, accompanied by his wife Jean, made a tour of the USA. The relationship between Houdini and Doyle started well but soured after Doyle’s wife famously brought a spirit message back from Houdini’s deceased mother. It would not have been uncharacteristic of Houdini to have found an opportunity to say he had fooled the creator of Sherlock Holmes, especially when writing in A Magician Among the Spirits (1924) in which he refers to Doyle many times including their meetings in 1922.
Similarly, Doyle wrote about Houdini but never mentioned this encounter or the trick. Had he forgotten how much it had fooled him?
During his tour of the USA Doyle met Houdini a number of times. A list of them can be found in A Chronology of the Life of Arthur Conan Doyle written by Brian W Pugh. Pugh has tried to chart the almost daily and significant activities of Doyle during his life. And his book shows that Doyle met Houdini at least twice at his home during May and was always accompanied by his wife Jean. Jean does not appear in Ernst’s account.
All the solutions so far offered are theoretical. No one has tried to build or perform their solutions which I think would be an interesting project. I suspect it would be difficult to make it work as effectively as Ernst suggests. It’s not just the conditions under what the trick is performed that make it difficult it’s the fact that Ernst is a magician himself. He would almost certainly know of Berol’s illusion and yet doesn’t mention it in his story. As Houdini’s lawyer he might even have been involved in the purchase.
Max Berol toured extensively with his illusion including the UK. It was a highly paid and sought after act. Given its nature there was always a chance that Doyle knew of it which makes it all the more unlikely that Houdini would have tried to baffle him with a version of a trick that had toured the world and even worked the London Hippodrome.
And what are we to make of the coincidence between the title of Berol’s illusion, Menetekel and the words that Doyle chose to write down? The obvious connection is the story in the Bible (Book of Daniel) from which the phrase originates but there’s no indication in the account that Houdini said to Doyle write something down and I will produce that writing on this board. Could it be that Ernst was describing the Berol illusion and so gave those words to Doyle when telling the story?
Berol’s Menetekel illusion wrote only one word at a time on the board probably because you’d run out of ink trying to write a sentence. Even with a three-quarter inch ink-soaked cork ball in your hand you would be hard put to write ‘Mene, mene, tekel upharsin’ across an eighteen-inch slate. That’s a lot of letters in a small space. Now trying doing the same thing with a hidden assistant writing it in reverse or using some electronic mechanical contrivance as described by Bob Loomis.
Furthermore, what happened to that apparatus? Shouldn’t it exist somewhere along with everything else that remains of Houdini’s stage gear? What happened to the Max Berol apparatus that Houdini bought?
Finally, why did Ernst wait until both Houdini and Conan Doyle were dead to share this story? He was a prominent amateur magician who published in magic journals. He had ample opportunity to tell his tale.
None of this doubt prevents Bob Loomis’ book being an interesting read. There’s much to enjoy in the detail he uncovers about the characters involved. And it would still be an interesting project to build the illusion. One magician who has created a similar illusion is Paul Kieve. You'll find it in the stage production of the Roald Dahl story Matilda.