Just in case you thought drills are the product of 21st century home improvement television programs, maritime archaeologists have proof that bow drills were used as far back as 400 B.C. by the Greek Phocaeans who resided in the western area of modern-day Turkey. (Actually, bow drills are well known even earlier, and were recovered, for example, from the Uluburun Shipwreck dated to the end of the 14th century BCE).
In contrast to the rather mundane uses of modern drills (mainly drilling holes for construction), bow drills were multipurpose – aside from serving for drilling and construction purposes, the bow drill also made fire and was an important tool widely used in wood working, boat building and even dentistry.
A wooden bow drill was found on the Ma‘agan Mikhael Shipwreck discovered in 1985 70 m off shore Kibbutz Maagan Mikhael, along Israel’s Mediterranean coast. The ship was excavated, dismantled under water, conserved over a period of seven years and reassembled at the Hecht Museum at the University of Haifa. The artifacts including the bow drill were excavated and retrieved for research in the laboratory on shore. However, from the bow drill only the wood remained, with a hollow and several small wooden cleats that apparently secured a bit; its metal did not survive. Recently, as part of the conservation procedure for this unique item, archaeologists cleaned the drill, including its inner recess, and found minute remains and traces of metal, but its characteristics are not known. The shape of the recess inside the wood could not be traced, nor could we ascertain the shape of the metal bit that did not survive.
Yaacov Kahanov, Head of the Leon Recanati Institute for Maritime Studies, notes that this particular wooden drill is well preserved. “We want to understand how the tool was structured. What kind of metal served as the drill’s bit? What was its shape? How was the carpenter / shipbuilder able to ensure that the bit wouldn’t come loose during usage?”
Using RayzorX Pro digital radiography system, the bow drill was X-rayed from several angles. The detailed, sharp images resulting from averaging and the use of cutting-edge enhancement tools indicated that remnants of metal were still present in the wood although the bit had disappeared. Prof. Kahanov notes: “The X-ray images indicate that there was an iron blade embedded in the wooden bow. The blade obviously corroded, staining the wood and leaving traces of metal behind.”
He adds: “Rayzor Digital Radiography imaging even enables us to see the grooves left by the bowstring. But aside from this, the sharp X-ray images indicate that the blade’s bottom section was square, a shape which artisans apparently realized a century ago optimizes anchoring and stress-resistance. The structure of the tool is brilliant, but we wouldn’t have been aware of this if it weren’t for the advanced digital X-ray equipment used.”
The Brooklyn Museum in association with D. Giles Ltd., published in 2013 a catalogue called “Soulful Creatures, Animal Mummies in Ancient Egypt” with essays written by curators and preservers Edward Bleiberg, Yekaterna Barbash and Lisa Bruno and a forward by Arnold L. Lehman. The catalog explores the phenomena of animal mummifying (millions were mummified) and the utilisation of modern research techniques in the effort to preserve as well as research and learn about the rare artefacts. The catalog is corresponding to an exhibition by the same name, which is part of an ongoing program at the Brooklyn Museum to share the less familiar or even unknown treasures of the museum’s Egyptian collection with a wider audience. The exhibit and catalog, both published in 2013, are the results of a project that started with the discovery of 30 forgotten animal mummy boxes in the vaults of the museum in 2009.
The catalog and exhibition represent a cross disciplinary method to understanding and preserving the ancient artefacts. The combination of archaeological expertise and Egyptology knowledge along with scientific preserving methods, as well as consulting with medical scientists and other specialists in order to make the most of modern technologies in the inspection and analysis of the artefacts. New insights have been achieved through chemicals analysis, carbon-14 dating, CT scans and digital X-ray inspections. The exhibition puts the rare artefacts on display to the public but also shares the research methods used to study them.
In her article “The Scientific Examination of Animal Mummies, which is included in the above mentioned catalog, Lisa Bruno writes that mummified animals were discovered on a massive scale of millions. Like in a good CIS television drama, the preserver in the museum sets about to reveal the secrets harboured in the animal remains. The objective of a meticulous scientific examination of the animal mummies is to try and tell their story. The story lies in the little and exact details of each specimen. Scientists are looking for the motivation of animal mummifying are trying to use the evidence collected to build ideas and theories about this mysterious practice.
In contrast to early studies of mummies and ancient artifacts (as early as the first expeditions undertaken by Napoleon Bonaparte) the mummies no longer need to be destroyed in order to be researched. Modern nondestructive technologies are available. X-rays were discovered by Wilhelm Conrad Roentgen in 1895 and they were used in a study of artifacts as an imaging tool as early as 1896 (as described in an article by the scientists Carl Georg Walter Koenig). Even portable X-ray is recorded in those early days – in 1896 a British doctor Charles Thurston Holland radiographed a bird mummy on an Egyptian tomb site. In the Brooklyn Museum an X-ray of a dog mummy was taken as early as 1939. Today, with digital radiography and CT scans, the imaging capabilities of the researchers are enhanced tenfold!
In preparation for the exhibition, the Brooklyn Museum conservation laboratory team, led by Kenneth Mozer, were not limited to eye vision only. Lisa Bruno writes that they analysed the animal mummies with tools such as stereomicroscopes, various strengths of electromagnetic radiation, X-rays and Computed tomography (CT). These various imaging tools allowed the researchers to view the rare artefacts in different ways and levels. Imaging tools were also used for analytic methods – such as X-ray diffraction (XRD) and gas chromatography (CG). Other techniques such as Carbon 14 dating, archaeological grounding and historical deduction were used to complete the picture. The combination of different scientific resources is important to such a study. No single discipline can provide comprehensive results when investigating these mysterious objects.
Seeing Inside the Mummies
X-ray is a form of electromagnetic light, which moves in a wave pattern that ranges out of the human eye vision capability. X-rays are short light waves and thus they can be very intensive and powerful, penetrating and passing through most materials and blocked only by denser substances such as metal or bone. In the traditional film X-ray image, dark areas demonstrate very little material (black means nothing but air) whereas white areas are seen where a dense material such as bone has blocked out the X-rays. Various levels of grey demonstrate a range of various material densities. Thus a two dimension image is created depicting a 3-dimensional object.
Today the Brooklyn Museum is at the cutting edge of X-ray technology and owns and uses the RayzorX Pro portable digital radiography system for the nondestructive inspection of its mummy collection with X- rays. The image is generated by the X-ray and is immediately and directly recorded as digital data. Lisa Bruno mentions that this instantaneous imaging is an advantage to the conserving researchers, because the results are immediately available for analysis and any manipulation or repeated imaging can be done on the spot, without repeated transport of rare artefacts. The radiation intensities can be adjusted for the materials present in the specimen that is being examined, thus providing clearer and more articulated images.
Examples of X-ray analysis and techniques are various. Controlled exposure levels can help review the mummy and the materials it is made of in various layers, by exposing the relevant scale (and representing a certain material density) in each different image. For example, an image can concentrate on displaying bones, while the linen wrappings of the mummy are “removed” by controlled over-exposure. Under-exposure can help see the less dense linen of the mummy, this time sacrificing the visibility of bone details. Digital radiography also enables researchers to view the image as a positive reading (meaning bones will be black). This helps researchers in the analysis of the results.
X-ray of mummies can reveal surprising evidence. In Figure 2, the Ibis shaped mummy revealed to contain the bones of snakes. The symbolism or ceremonial value of such a “mixed” item is not clearly understood.
An elaborated Ibis mummy which takes the form of a human body with a carefully wooden carved Ibis head is a wonderful demonstration of external precision and exactness, which is seemingly contrasted by its contents – only a few random bones can be seen in the X-ray image (see Figure 3) instead of the expected careful placement of body parts. However, the careful arrangement of the mummy is clear when one looks at the cross section CT scan of the mummy bundle, in which it is made clear that the bundle is stuffed with feathers.
Mummies that do not contain whole animals were traditionally known as “fake” or “false”. With such a spectacular wrapping, the incomplete contents of the Ibis bundle were a surprise to the researchers. The CT scan revealed the meticulous arrangement of the animal, so that it became clear that even though the contents are not a whole animal, this mummy was costly to make and was of the highest standards and could not possibly be faked. It is now believed that such incomplete mummies were created as a result of lack of resources to meet demand. Another motivation may be that such a high budget mummy was used to preserve the remains of a certain animal, perhaps the incomplete reliquaries of saints and other religious figures.
Mummies that contain only one bone of a large animal are considered also to be representations in a more votive or reliquary sense. An X-ray of a bovine bone fragment is clearly seen in a mummy which is shaped as a miniature bull (see Figure 4).
Modern technologies have enabled conservators to establish new understandings and theories about the motivations leading to the making of animal mummies and the methods used to make them. However it is not to be expected that modern tools will provide all the answers to the mysterious and complex mummifying tradition. Some principles seem to apply widely, but there is an abundance of material variety, creativity and a large time span in which the mummies in the Brooklyn Museum's collection have been constructed. Modern tools enable complex technical data to be collected. Its availability will enable a more comprehensive analysis, using various disciplines for its interpolation. Modern science provides highly suggestive practical evidence and a good basis for theory, as well as new and enhanced results for the better understanding of enigmatic historical objects. But the true answer to the purpose of animal mummies in the larger context of ancient Egypt remains part of the puzzle curators, archaeologists and conservators are trying to solve.
We are proud that our X-Ray equipment is being used for such an important project of culture preservation.