Imaging the Codex Xolotl and Mapa Quinatzin

Imaging the Codex Xolotl and Mapa Quinatzin at the Bibliothèque National de France, Paris, 14-15 June, 2016

Written by Jerome A. Offner, Ph.D, HMNS Associate Curator, Northern Mesoamerica

On June 14 and 15, Dr. Antonino Cosentino of Cultural Heritage Science Open Source and I were able to carry out technical photography of the Codex Xolotl and Mapa Quinatzin at the Bibliothèque Nationale de France, Paris (BnF).  Permissions, facilities and staff time were arranged by Laurent Héricher, Chef du service des manuscrits orientaux, Département des Manuscrits of the BnF.  This was no easy task and we express our appreciation for the extensive effort and work he put into these arrangements, particularly in the midst of a multiyear renovation of the site Richelieu, where the documents are kept. Loїc Vauzelle, a graduate student at the Sorbonne, travelled from central France at his own expense to assist, and John Hessler, the Kislak Curator of the Library of Congress also happened to be in Paris and provided expert aid and observations as the process went on.  In addition, Dr. Marisa Álvarez Icaza Longoria of UNAM, who was at the BnF traveling on a fellowship, contributed valuable ideas. She had just participated in the Oxford conference “Mesoamerican manuscripts: new scientific approaches and Interpretations,” held 31 May to 2 June, 2016 which included several talks on imaging indigenous Mesoamerican documents.

The project had been scheduled weeks in advance, but emerging problems nearly led to its cancellation.  The Seine was at or out of its banks in Paris as part of the worst flooding in decades.  The Louvre was moving some of its holdings out of danger.  Certain sites of the BnF were closed.  France was also hosting the 2016 UEFA European Football (Soccer) Championship and Air France pilots began a strike on the day before my flight from Houston to Paris.  Nevertheless, we were able to complete the project and Paris began to resemble its familiar beautiful self at just about that same time. 

Seine receding from flooding at Île de la Cité,  16 June, 2016

Seine receding from flooding at Île de la Cité, 16 June, 2016

Notre Dame, in evening light, June 16, 2016, as the skies began to clear

Notre Dame, in evening light, June 16, 2016, as the skies began to clear

At the BnF, site Richlieu, we were provided with a meeting room with two windows that we were able to cover with two layers of black plastic bags secured by green painter’s tape. For others who may be faced with a similar situation,  it is worth noting that not one but two layers of these already two sided bags were needed to block the summer light sufficiently. Also, the BnF was happy to see that the painter’s tape left no marks on their walls upon removal. The meeting room door turned out to be light proof around its edges and needed no special attention. The room had only a standard meeting table, the height of which unfortunately could not be adjusted. 

We were able to capture four types of technical images for these Aztec pictorial documents.  Antonino Cosentino used a modified full spectrum Nikon D800 digital camera, sensitive to the spectral range 360-1100 nm, along with different lighting sources and filters to obtain images that we can designate in this way:

VIS (visible)
IR (infrared)
UVF (ultraviolet fluorescence)
UVR (reflected ultraviolet)

Because of the table height, we had to shoot at an angle, but Antonino made the best of this by making the IR images do double duty also as RAK images. 

Preparing to acquire images from Codex Xolotl X.020

Preparing to acquire images from Codex Xolotl X.020

Dr. Cosentino focusing in on Codex Xolotl X.050 and X.060

Dr. Cosentino focusing in on Codex Xolotl X.050 and X.060

Technical photography documentation of the manuscripts.

What do these designations for types of photography mean, and how are the images described by them acquired?

VIS is used here for light in the visible spectrum, or the portion of the electromagnetic spectrum that is visible to the human eye. A typical human eye will respond to wavelengths from about 390 to 700 nm. In the procedure used for the documents, light, provided by fluorescent tubes, reflected off the surface of the document and passed through an X-Nite CC 1 filter which blocked infrared wavelengths before entering the lens and camera.  The filtered light was then captured by the 36 megapixel CMOS sensor in the Nikon camera. 

IR is the designation used here for infrared photography.  In this case, a Heliopan RG 1000 filter was placed over the camera lens to block visible light while allowing infrared radiation into the camera. (Remember here that infrared radiation has longer wavelengths than visible light, while ultraviolet radiation has shorter wavelengths).    As mentioned, these IR images also served as RAK images, meaning that the document pages were illuminated by an infrared source at an oblique angle.  Although the angle we used was only slight, the images captured provide a great deal of information on the surface topography and relief of document pages. 

UVF imaging picks up visible light emission excited by a UV source (UV-LED) that is used to illuminate the document.  As the surface is illuminated, certain materials fluoresce—that is, the material absorbs some of the UV radiation that falls on it and emits visible light.  The photons which are then emitted from the document have longer wavelengths that fall into the normal visible light spectrum.  Not all materials fluoresce so this method can be a valuable tool for distinguishing materials, and for seeing certain materials more clearly, such as European iron-gall ink glosses (see below). For UVF, two filters are placed in front of the camera—the X-Nite CC 1 filter mentioned above, and a Baader UV/IR filter.  These filters work together to create a spectrum window that allows just the visible wavelengths produced by the UV-induced fluorescence into the camera, while blocking wavelengths of light outside the visible spectrum.

UVR (reflected UV) imaging is simpler.  The document is illuminated with UV light and the camera records the reflected light through another spectrum window created by the X-Nite CC 1 filter and a B+W 403 filter which allows UV waves into the camera. UVR photography is also another helpful tool for assessing surface topography and roughness. 

The images are taken sequentially without moving the document and can therefore be assembled into spectral cubes in Photoshop through the use of layers.  Using features of this program, and harnessing the human eye’s exquisite sensitivity to detecting change, the various layers can be compared using a method not unlike the blink comparator that was used by Clyde Tombaugh to discover the dwarf planet Pluto in 1930. 

The filter set used for the examination of the manuscripts.

The filter set used for the examination of the manuscripts.

Understanding how the images are acquired helps us understand what we are seeing but also helps us develop methods to uncover or clarify details in these nearly five hundred year old manuscripts. Examining the surface of the images is also not unlike examining the images sent back by NASA planetary probes.  Below, the ice rafts on Jupiter’s moon Europa are seen side by side with rafts of “plaster” (gypsum, chalk, we still need to characterize this material) from the surface of the Mapa Quinatzin.  Many, but not all, Aztec manuscripts were painted after a layer of “plaster” had been applied on top of indigenous amatl (amate) paper.

The filter set used for the examination of the manuscripts. spacecraft on February 20, 1997, from a distance of 5,340 kilometers. Image Credit: NASA/JPL/ASU

The filter set used for the examination of the manuscripts. spacecraft on February 20, 1997, from a distance of 5,340 kilometers. Image Credit: NASA/JPL/ASU

 

Mapa Quinatzin, leaf 2, upper margin

Mapa Quinatzin, leaf 2, upper margin

We need to examine our images as carefully as NASA, JPL, and ASU examine their images, bearing in mind that it is considerably easier to acquire new images of the Mapa Quinatzin than of Europa. 

In our case, let’s compare the VIS image with the IR, UVF and UVR images.

four-squares

In this example, the damaged plaster fragments are seen well in VIS and UVR, while the IR image more accurately depicts the folding and flexing of the supporting indigenous amatl paper, and the UVR images shows mostly disturbance in the underlying amatl paper. 

Every landscape we encounter in the two documents that we imaged has the potential to teach us something new. For example, a detail from Mapa Quinatzin, leaf 3 helps us read the alphabetic gloss in European ink better than it has been read for centuries. Indigenous ink, composed of carbon black, is far more durable and less damaging to indigenous documents.  The often corrosive European iron-gall ink happens to absorb UV radiation and so UVF can be a useful tool for reading alphabetic glosses on these documents because of the contrast with the support (amatl paper) that is generally brighter (because it fluoresces).  This section of the manuscript (below) was unfortunately trimmed during its long history and the meaning of this particular scene, showing a man conversing with someone in a building, along with a man punished by strangling, has remained obscure. 

Mapa Quinatzin leaf 3 records a few Aztec legal rules along with cases of judicial corruption and their punishment. It is not just a list of rules but instead a fragmentary statement of precontact Aztec Texcocan jurisprudential thought, most likely presented, in this case, for European inspection.  Such jurisprudential thought continued well after contact, and involved such issues as how Aztec legal process should be conducted and how certain cases with certain details should be decided and punished.  Aztec jurisprudence was the product of sophisticated schools of thought over many years.   

four-squares-2

In this set of images of a small part of Mapa Quinatzin, leaf 3, the UVF image is improved and rendered legible by the fluorescing of the support (the amatl paper) in contrast to the dark European iron-gall ink in the gloss.  The Nahuatl text in alphabetic form that is revealed, of course, explains only a tiny portion of the meaning of the images: the indigenous Nahuatl graphic communication system was capable of communicating far more than mere alphabetic text could in a given amount of space.  Nevertheless, what little the alphabetic gloss says helps us correlate the image with other lengthier dependent alphabetic texts, especially those of the expert early ethnographer and historian Ixtlilxochitl (1975), and yields enough information to change our understanding of the structuring of the indigenous content of Mapa Quinatzin leaf 3 and of Aztec jurisprudence as a whole.

The landscape provided by the new images is not as large as Jupiter’s moon Europa, but it is a significant undiscovered country that will provide many more surprises as it is examined.  What was unknown proves again to be only temporarily hidden, and more things that remain unknown will hopefully be revealed through these images or through carefully designed new images and imaging techniques. 

 


More about Jerome A. Offner, Ph.D, Associate Curator, Northern Mesoamerica

Jerome A. (Jerry) Offner began working as a volunteer with the museum in 1984 and curated two exhibits on aspects of the Americas in the 1980s. Jerry is an expert on the Aztecs of Mexico, their history, culture and overall graphic communication system, including their writing system.

In 1983, Jerry “wrote the book” on the Aztec legal system and has continued to conduct research and publish articles through the present day on topics including religion, economics and history. He specializes in the beautiful and colorful “codices” or native pictorial documents from before and after the Conquest in 1519 AD. Currently, he is assembling a team in Europe to investigate the greatest of the Aztec pictorial histories—the Codex Xolotl from the city of Texcoco, which reports on many events of the remarkable life of Nezahualcoyotl who ruled that city 1431-1472 AD. This history, kept in the Bibliothèque Nationale de France in Paris, illustrates in considerable detail more than 260 years of history before 1431 AD on eleven pages and three fragments made of native paper. It records the migrations, invasions, wars, marriages, births, and lives in the histories of the many different peoples who came to be known as the Aztecs in what is now the central part of Mexico.

Jerry is also an expert in contemporary masks and textiles of Mexico, with additional interests in Africa and the ancient Mediterranean. He read, writes or speaks English, Spanish, French, Latin, ancient Greek, and classical Nahuatl, the language of the Nahua (Aztecs) of Mexico.

“Museums are for the adults in children and the children in adults,” says Jerry. “Most of us remember our first visit to a museum and how the entire day seemed to go by in a flash. We also remember our children’s first visits to museums. Museums are essential in providing hands on experience and interaction with actual objects in our increasingly virtual, digital world.

They anchor us to what is real and at the same time provide inspiration for childhood intellectual development as well as lifelong learning.”

Jerry received his B.A. in 1972 from the University of Chicago and his MPhil and PhD from Yale University in 1975 and 1979. He was been awarded grants by the National Science Foundation, the Doherty Foundation, as well as the Fulbright program. His book was awarded the Howard F. Cline Prize in 1985.

He is active in presenting papers at professional meetings, both in English and Spanish  Modern Texcocans remain fiercely and justifiably proud of their long history.  On September 2, 2016, he will give the “conferencia magistral” within the at the Tercer Coloquio de Historia Regional de Texcoco, in the modern city of Texcoco 2016, within a few hundred meters of the sites of some of the events depicted in the manuscripts included in the blog post.  He will be presenting important new findings based on the images newly acquired in Paris.

Glow on, get happy! Join HMNS this Friday for a fun-filled night of light at LaB 5555: GLOW

Whether they’re toys that shine in the night, black lights, glow sticks or fireflies, things that produce an eerie glow are fascinating. Give a kid a glow-in-the-dark toy or paper her ceiling in dimly shining plastic stars, and she will be occupied forever. She’ll find ever brighter lights to charge them up, ever darker places to view them for maximum glow effect, and generally love exploring how it all works.

You know this; you were that kid. So what’s the deal with the glow?

Enjoy a sip of the galaxy -- learn how to make this glow-in-the-dark cocktail at Neatorama

Learn how to make this amazing looking glow-in-the-dark cocktail over at Neatorama

It’s 10 p.m. Do you know where your electrons are?

While there are several “flavors” of things that glow, they all have something in common: Things glow because photons are emitted when “excited” (at a higher energy state) electrons drop back to a lower, more stable state. Aside from promising them a pony or a tour of CERN, there are several ways to get your electrons excited.

In chemical glow sticks, a chemical reaction excites the electrons. This process is called chemiluminescence. Glow sticks are an excellent way to experiment with reaction rates and temperature. If you want the reaction to last longer, follow a kid’s advice and put the glow stick in the freezer or in ice water so the reaction slows down; it’ll take longer to use up the chemicals in the glow stick. The trade-off is that because the production of photons is also slower, a cold glow stick is dimmer than a warm one.

Fluorescence is like light recycling. Fluorescent rocks, laundry detergent additives, paint, and even some animals can re-emit light after something shines on them. Usually we’re talking about things getting hit with ultraviolet or ‘black’ light and re-emitting within the visible spectrum. This makes sense because as you progress along the spectrum of electromagnetic radiation, visible light is a bit lower in energy than ultraviolet light — you can’t expose something to lower energy red light and get it to fluoresce in UV, for example. Fluorescent things certainly fluoresce in daylight, but not enough to outshine the ambient light, so they’re most noticeable under a black light in an otherwise dark space.

Phosphorescence is a lot like fluorescence but stretched out over time — a slow glow. So you can shine light (visible or UV) on a glow-in-the-dark star and it re-emits light, too, but over a lot more time, so the glow continues for minutes or hours before it completely dies out. If you have a glow-in-the-dark toy or T-shirt, try “charging it up” with lights of different colors or intensities and checking out the glow that results.

Nature glows

Fireflies produce and use their own chemicals, luciferin and luciferase, to dazzle and attract potential mates — and sometimes to lure prey. A surprising number of marine critters are bioluminescent, too, like dinoflagellates (plankton) that glow when disturbed, the angler fish, and some squid (perhaps they are blending in with starlight from above). Headlines occasionally announce a new genetically engineered “glowing” kitten, rabbit, plant, sheep, etc., but they are almost always talking about fluorescence instead of bioluminescence, so the light is only seen when the animal is placed under ultraviolet light. (One useful application of this is the ability to track a protein related to a certain disease by getting the introduced gene for Green Fluorescent Protein (GFP) to link to the gene for the protein of interest). Some animals like scorpions and jellyfish (the original source of GFP) fluoresce naturally.

Cheap thrills

Sugar and adhesives can exhibit triboluminescence, in which friction or fracturing produces the light. This one is great to try out at home; you just need Wint-O-Green Lifesavers®, transparent tape and a very dark room (a buddy or a room with a mirror is helpful for the Lifesavers portion). Dr. Sweeting (that’s her real name) has more detailed instructions and explanation, but the big idea is that a tiny, but visible, amount of light is emitted when you peel tape off the roll and when you bite into the candy, crushing sugar crystals against each other. The wintergreen oil even improves the effect by fluorescing!

Are there any other kinds of luminescence? Yes! Incandescence, piezoluminescence, radioluminescence, etc. But that’s enough fun for one post. Go try out triboluminescence!

Just can’t get enough? Make sure to come early for the educational portion of HMNS’ LaB 5555 this Friday for more GLOW fun, and learn all about the science of what gives things light. I’ll be there doing demos to light up your night. For tickets and more info, click here!

Texas Wins Big: NEED State Program of the Year

NEED – the National Energy Education Development Project – is an organization that teaches people how to teach about energy. Even though the concept of energy education might sound simple at first – too many people think that if they teach about one energy source, they’re teaching about energy in general.

In the NEED Primary Science of Energy curriculum, they discuss petroleum, coal, solar energy, uranium, biomass, hydropower, wind energy, geothermal energy, propane, natural gas and light.

Texas was selected as NEED’s State Program of the Year because of the diverse and dedicated partners providing energy education opportunities to students, teacher, and families in Texas.

HMNS, along with other Texas partners, was recognized at the 29th Annual Youth Awards for Energy Achievement for the Museum’s commitment to NEED and the programs in Texas, as well as our commitment to energy education in general.

Niagara Falls Hydro Plant
Hydropower
Creative Commons License photo credit: gobanshee1

But it’s not just about giving the teachers facts and figures. The fastest way for teachers to get students excited is to get the teachers excited –  and NEED activities do just that.

Before receiving the award, we completed a test run of their new hydropower curriculum. I spent a few hours with elementary school teachers and kids, putting together a water-powered wheel that would lift paperclips.  The exciting part was watching the kids come up with ideas and innovations to make the water-powered wheels run more efficiently and do more work.

To learn more about energy education, check out our previous entries in the blog’s Energy category.

Sept. Flickr Photo of the Month: Museum Reflected

Our science museum is lucky enough to have talented and enthusiastic people who visit us every day – wandering our halls, grounds and satellite facilities, capturing images of the wonders on display here that rival the beauty of the subjects themselves. Thankfully, many share their photos with us and everyone else in our HMNS Flickr group – and we’re posting our favorites here, once a month. (You can check out the first two picks: “Leaf’s Eye View,” by AlphaTangoBravo and “Rice Paper Butterfly” by emmiegrn.)

There are so many stunning images in the pool, it’s always tough to choose. This month’s pick, “Museum Reflected” by bryan.dawson is a striking portrayal of something most people don’t examine too closely – the globe on the tip of our sundial. Here’s what bryan.dawson had to say about his shot – which includes an interesting perspective on composition:

“It was only recently that I even realized that you could take photos in most of the museum. It wasn’t until one of my Flickr groups, Assignment Houston, had an assignment at the museum that I even considered taking my camera along. I missed the big group gathering (you might have seen it mentioned on the HMNS blog as well), so I went on my own later.

I think I drove my fiancee mad since I stopped every few feet to take a photo. This particular photo was one of the very last ones I took that day. My fiancee wanted to look around the gift shop, so I went outside to snap a few. The clouds were blocking the sun just enough to send out some tendrils of light. It was a beautiful sight, but I knew it would look better if there was something in the foreground. That’s when I noticed that the ball on top of the sundial was mirrored and you could see the museum reflected back in it.

That was it … I lined it up, and what you see is the result. I tried lots of different post-processing on it before deciding upon a monotone coloring. I like to think it lets you focus on the composition instead of being distracted by the colors.”

Many thanks to bryan.dawson for allowing us to share his beautiful photograph. We hope this and all the other amazing photography in our group on Flickr will inspire you to bring a camera along next time you’re here – and show us what you see.