Artful letter closures from 1831

In issue 320 of the British Origami Society magazine (February 2020) I had an article entitled “Two Early Letterfolds” about folding instructions for two letterfolds in two old German books, Leichte Künsteleien (1819) by Dr Heinrich Rockstroh and Das Buch der Zauberei (1835) by Johann August Donndorff. They were early examples of the use of diagrams to explain paperfolding. A copy of the article is included here.

BOM Article_Two Early Letterfolds
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Since then I've come across another book by Dr Heinrich Rockstroh which again includes the Puzzle Purse, but also another folded paper item also referred to as a letterfold. The book is called Mechanemata oder der Tausendkünstler (1831), and luckily for us it's available in digitised form via Google Books. It’s a large collection of the kinds of tricks, amusements and scientific experiments that were popular at the time, compiled from various sources. “Mechanemata” is Latin for “mechanisms” or “tricks”, and “Tausendkünstler” is a German term for “magician” or someone who is "skilled in many things". There are copperplate illustrations at the end of the book showing some of the items described, including both the letterfolds.

Copperplate illustrations from Mechanemata (1831)

Mechanemata actually has a lot of interesting material in it, including several of the paper-related tricks I've covered elsewhere in this blog. I hope to look at some of these in future posts, but for now I'll just focus on the two letterfolds, which Rockstroh describes as "artful letter closures".

The Puzzle Purse

The written instructions for the Puzzle Purse (page 125) are a little simpler than those found in Rockstroh’s earlier book Leichte Künsteleien, and the diagrams slightly more detailed. This seems to be the source which Donndorff borrowed from for his description and diagrams in Das Buch der Zauberei.

An artful letter closure

The sheet of paper chosen must be as long as it is wide. You can quickly be sure of this if you fold the sheet so that two initially adjacent edges lie one on top of the other.

First fold the sheet, as shown at the top left at 1 on the fourth copper plate, so as to make nine equally sized squares, and also twice so as to produce two creases from one corner to the other or two equally sized triangles each time. All the creases are visible on the side of the sheet with writing on it, and are not raised but indented. Then make a diagonal fold on each of the outer central squares, the same as on the outer square to its left, and so that the paper is folded over and not under as with the previous folds, and therefore these four folds are raised on the side of the sheet with writing on it, not indented like the others.

Now, using the outer triangles, try to fold the sheet together so that the surfaces of triangles a and b, triangles c and d, triangles e and f, and triangles g and h lie against each other, and the diagonal folds on the outer central squares lie on the middle of the small inner square, so that the whole thing is as shown at 3 on the left. Now fold the outer triangles over one on top of the other. But slide the last of these triangles underneath so that part of this triangle is itself under the first triangle; in this way when the sheet is properly closed it looks the same on one side as on the other – as at 3 on the top right in the drawing on the same copper plate.

Nowadays the instructions would be a bit more concise and easier to follow, and would probably look something like this:

The Cross Letterfold

The second letterfold in Mechanemata (page 267) starts out like the traditional Japanese design Yakko San, but then has the small corners folded inwards at the end. At least, that's how I first saw it. I asked David Mitchell, who knows a lot more than I do about early Japanese folding and has a page on his website devoted to Yakko San. He quickly pointed out that the same basic fold was also found in Europe at around the same time, but as a napkin fold usually known as The Cross.

The Cross is still found in modern napkin folding books. See also Joan Sallas' Gefaltete Schönheit (now also available in English as Folded Beauty), which traces the complete history of tablecloth and napkin folding. Barth and Niederley described it in Des Kindes erstes Beschäftigungsbuch (1876) as a basic fold for making origami clothing, and Friedrich Fröbel included the same form in his paperfolding work for kindergartens. It's also the basis for an old model usually referred to as a Steamboat or Battleship, which appears in a number of early origami books.

Des Kindes erstes Beschäftigungsbuch (1876)

by E. Barth and W. Niederley

For Rockstroh’s second letterfold, take a square sheet of paper and write a letter on it. Fold the four corners in to the middle (i.e. make a blintz), then proceed as follows:

The first four drawings come from Plate 4, but the last two are at the bottom of Plate 2. There are a couple more at the top of Plate 2 that look as if they might be related, but these are actually Klangfiguren or Chladni Figures. If you’ve never heard of Chladni Figures before (as I hadn’t), a quick Google search will reveal all.

To be honest it’s not really very practical as a letterfold, but it would certainly be more interesting to receive a letter folded like this than a sheet of paper simply folded into two.

Why "artful letter closures"?

Both letterfolds appear under the heading Künstlicher Zuschluss eines Briefes, which I've translated here as “artful letter closure”. In modern German künstlich normally means "artificial" and often has the same slightly negative connotation as in English, suggesting something unnatural or inauthentic. But from online copies of dictionaries dating back to the mid-19th century it seems that in both languages the usual sense back then was more like that of “artful” or “clever”.

The main point of interest in all this is of course the early appearance (almost 200 years ago) of relatively modern-looking origami diagrams. The second letterfold in Mechanemata is also intriguing because it's an adaptation of a known fold that doesn’t seem to appear anywhere else in exactly this form.