Ur Project: December 2014

January 2, 2015

Tool Complete with Handle (Again)
Comparisons to and a closer look at U.8783 (Penn Museum Nr. B17463)
Awl, Chisel, or Punch from grave PG 422

With the expansion of the Penn Museum’s scientific lab and teaching space (Center for the Analysis of Archaeological Materials, CAAM) the Museum has acquired a digital x-ray suite. This new equipment allows us to take a closer look at and inside objects. A good candidate for investigation is the awl from PG 422 we saw last month. With x-rays, we can look beneath the bitumen handle.

[Though the X-Ray suite is used by some members of CAAM, it is actually a part of the Conservation Department at the Museum and I’d like to acknowledge the assistance of Conservation personnel in obtaining the x-rays of this object, in particular the work of Tessa De Alarcon.]

X-ray of tool B17463
X-ray of tool B17463

I had expected to see a block of wood encased in the bitumen and wanted to find out if it had been carved in the distinctive bulb shape we see for many awls and for the external bitumen itself. Yet, the x-ray doesn’t show a block of wood at all. It’s possible that the wood is approximately the same density as the bitumen and that it therefore doesn’t show, but that doesn’t seem all that likely. Another possibility would be that wood chips were used to stabilize and harden the bitumen into a usable handle. In fact, additions to bitumen are commonly used since the pure material is not very solid. Just as temper is used in clay, bits of harder material were often included in the bitumen mix just as is done with asphalt for roads today. In that modern case, bitumen is the binder for crushed rock, gravel, or sand. Ancient Mesopotamians knew they needed this mix and pot sherds that are sometimes found covered in bitumen mixture probably show their use as mixing bowls.

Crushed shell was common as a strengthening agent as were vegetal and mineral additives. Such mixtures are seen in bitumen used for waterproofing as early as the Ubaid period (see for example finds at the H3 site in the As-Sabiyeh region of Kuwait). On the mixture of bitumen at this site, used to waterproof reed boats, Robert Carter states: “The vegetal matter, chopped reed and/or chaff, increased its flexibility and tensile strength.”

So it might be that chipped wood was used in the bitumen handle of the awl at Ur. This might explain the burning observed on the wood, since the chips could have been burned before mixing. Of course, the appearance of the piece through the missing bitumen area seems rather solid and the chips of wood would thus have been larger than would be expected for a stabilizing material.

X-ray of tool B17463, rotated 90 degrees from the previous image and at a different wavelength showing less of the bitumen.
X-ray of tool B17463, rotated 90 degrees from the previous image and at a different wavelength showing less of the bitumen.

The copper tool is quite long, reaching well back into the handle. It flares near the back and then returns to a smaller diameter, ending in a kind of narrow nail head. The copper itself is clearly less corroded in the area surrounded by the bitumen, which would be expected. But, would the bitumen, even with strengthening agents, have been able to support pressure on this tool without allowing the back end to press through and shatter the handle?

Another interesting x-ray revelation is that a hole appears in the back of the copper rod. The hole is placed near the widest point of the embedded portion, about 20% from the nail head end. There doesn’t appear to be a purpose for this hole. Perhaps the tool had been something else in a previous usage and the handle had been placed around it later? Or the hole was used to stabilize or attach the shaft in some way, perhaps by inserting a string through it to emerge from the sides of the handle?

Although our closer investigation has left us with more questions than answers, the utility of such examinations is clear. We would not have been able to approach an understanding otherwise without destroying the tool. CAAM and its scientific tools for analysis have thus helped us to pose new questions and approach new answers. And our new vision of the design of this tool can now be more completely compared to the design of others in our collection and in collections around the world.