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Musical Cryptography Fold-In

Updated: Nov 27, 2022

The Testament de Jérôme Sharp (1786) by Henri Decremps was one of the first books to provide detailed descriptions of card tricks and sleight of hand.

Don't worry, I'm not going to be looking at the card tricks, because (a) this blog is supposed to be mainly about paperfolding, and (b) others have already analysed the magic content of the book much more thoroughly than I could.

Unfortunately there's no actual paperfolding in Decremps' book, but it does include an interesting folding-related feature. At the risk of giving the whole thing away, I'll just say that the idea will be familiar to many from the famous MAD Fold-Ins by Al Jaffee (described here), and other fold-in pictures seen in more recent times.

It's going to take a bit of explaining, but bear with me.

The frontispiece of the Testament de Jérôme Sharp appears to show a musical score:

The text below the musical score reads as follows:

Une Devineresse voulant débiter ses oracles d'une manière mystérieuse, les écrivait quelquefois en notes musicales, comme


Pour mettre en état de bien lire la réponse ceux même d'entre les Consultans que ne savaient pas la musique, elle n'avait qu'à prononcer trois mots qu'on trouve dans cet ouvrage, Chap. I, Art. III.

A Diviner wanting to deliver her oracles in a mysterious way would sometimes write them as musical notes, as shown above.

To enable her reply to be read even by those of her suppliants who could not read music, all she had to do was to utter three words which can be found in this work, Chapter I, Article III.

If we go to Chapter I, Article III as suggested, we find the following:

The part that interests us is the first paragraph at the top of the page:

Il est bien facile de faire de l'écriture en musique quand on sait la lire; & pour la lire, il n'y a qu'à plier le papier; ces trois mots suffissent, avec la figure pliée qui est à la fin de l'Ouvrage, pour expliquer la Planche qui sert de Frontispice.

It is quite easy to do musical writing when one knows how to read it; and to read it, all we have to do is fold the paper; these three words are enough, together with the folded figure which is at the end of the Work, to explain the Plate that serves as a frontispiece.

The "folded figure at the end of the work" is a repeat of the musical score but with a different text. The digitised copy above from Google Books shows that someone has made horizontal mountain and valley creases at the points shown, and the page seems to be detached from the spine at the left-hand side so that it can be pleated along the creases.

Les note musicales qui servent de Frontispice à cet Ouvrage, ressemblent parfaitement au DISCOURS & à la MUSIQUE ci-dessus.

C'est la manière de plier le papier qui fait paraître l'un & disparaître l'autre.

The musical notes that serve as a frontispiece to this work look exactly like the SPEECH and the MUSIC above.

It is the way in which we fold the paper that makes one appear and the other disappear.

Again there is a strong hint that we should try to "fold the paper". If we do that, we end up with something like this:

By pleating the top part first we find that the musical score changes into words (though you may need to squint a bit to read them):

And then pleating the second part we get this:

Tu peux l'avoir perdu

mais on te l'a rendu

You may have lost it

but it has been returned to you

Which echoes the "sixth and last reply" that the Diviner gave to a young lady earlier on in the book:

Oui tu tiens ce bijou que d'autres ont perdu,

Du moins tu dois l'avoir, car on te l'a rendu.

Yes you have this jewel which others have lost,

At least you must have it, because it has been returned to you.

What does the oracle mean? And was it worth the trouble? I don't know, but it was interesting to see and fun to work out. Quite a lot has been written about Henri Decremps and the Testament de Jérôme Sharp but I've never seen any mention of this aspect of the book.

Musical cryptography

I haven't managed to find out much about "musical cryptography" online, but then again I haven't really looked very extensively either. Here are a couple of books I did find:

  • Kryptographik: Lehrbuch der Geheimschreibkunst (Chiffrir- und Dechiffrirkunst) in Staats- und Privatgeschäften (1809) by Johann Ludwig Klüber (page 274)

  • Handbuch der Erfindungen, Vol 7 (1814) by Gabriel Christoph Benjamin Busch (page 457)

  • Mathematical Recreations and Essays (4th edition, 1905) by W.W. Rouse Ball (page 258)

I won't reproduce the whole thing here, but the Handbuch der Erfindungen says this type of code was popularised by the French magician Comus, who lived from 1731 to 1807 (see Magicpedia):

"It is said that this invention originated with an officer who wanted to write secret orders, although I cannot vouch for this. What is certain is that the famous conjurer Comus in Paris was the first to popularise this musical note code."

And Kryptographik makes an interesting comment about the practicality of the technique:

"There is another type of secret musical note writing, but it is laborious and not really useful for long messages; it also arouses suspicion on account of the distorted and meaningless notes, and is then easy to detect."

In Mathematical Recreations and Essays (the first edition is from 1892, but the chapter on Cryptography first appeared in the 4th Edition of 1905) W.W. Rouse Ball talks about an earlier example of a musical cryptograph:

This last example has been reported in a few places over the years, but the details differ and no one seems to be able to say for sure which version (if either) is true. The website Cryptiana: Articles on Historical Cryptography says:

"However, some sources say it was sent to Charles II after the Battle of Worcester (1651), while others say it was sent to Charles Edward (Jacobites' Charles III) after the Battle of Culloden (1745). Moreover, there are two different versions of hiding the message in musical notes."

So although it seems that actual examples of this kind of musical code have been preserved it's not clear how seriously the technique is to be taken as a form of cryptography.

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