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Making stone vessels in ancient Mesopotamia and Egypt.

How were the fine stone jars and vessels of ancient Egypt and Mesopotamia made? An experimental test of materials and techniques explores the methods of early drilling.

Similarities between the Uruk and Jemdet Nasr periods of Mesopotamia (c. 3600--2900 BC) and the Gerzean and early dynastic periods of Egypt (c. 3500--2900 BC) include cylinder seals, the recessed panelled facade design in architecture, the use of pictographs, decorative art and the shapes of stone vessels. And craftsmen from Mesopotamia and Egypt necessarily developed similar tools and techniques for manufacturing stone vessels. In order to explore these similarities, I investigated the use of a specialized Egyptian tool in making a limestone vase.

It is generally thought that the cold beating, or forging, of truly smelted and cast copper into tools and other artefacts first occurred in Egypt around 3500 BC (Hoffman 1980: 207), castings being made in rudimentary open moulds at this period (Petrie 1917: 6). Coldforged, cast copper tools were also manufactured in Mesopotamia (Moorey 1985: 40--46). The technique of beating copper into sheets must have existed in both Egypt and Mesopotamia, where vessels of this metal were found at Ur by Sir Leonard Woolley (Woolley 1955: 30--31). Sheet copper is essential to the making of copper tubes, indispensable tools for drilling out stone vessels. It is likely that rolling copper sheet into tubes imitated nature's own architecure -- that of hollow reeds. The direct casting of copper into open, tubular-shaped moulds may also have been adopted by both civilizations.

Stone vessel manufacturing technology

In Mesopotamia, and Egypt, copper tubular drills were used for the initial hollowing of the interiors of vases and jars made from hard and soft stone (Woolley 1934: 380; Moorey 1985: 51; Reisner 1931: 180; Lucas 1962: 74). Striations are clearly visible on the inside walls of vessels, caused by the abrasive material employed with the drills. Although the stone-cutting, copper tubular drill has never been located, it would have been directly driven by a shaft of wood driven firmly into the top end (FIGURE 1a) and rotated by a bow-string (with the top of the shaft in a stone bearing-cap), or twisted clockwise, and anti-clockwise by wrist action. It is unlikely that shafts were rolled between the palms.

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Subsequently, Mesopotamian and Egyptian bulbous vessels -- those considerably wider inside than at the mouth -- were further hollowed by grinding with another tool, a stone borer of elongated form. The mid-point of its long axis was made to narrow equally from both sides. Seen from above, the borer assumes the shape of a figure-of-eight, enabling a forked shaft to engage with the waist. The top is normally flat, the bottom curved. In Egypt, this particular borer has been discovered at Hierakonpolis, a site associated with late predynastic and early dynastic stone vessel production (Quibell & Green 1902: plate LXII, 6) (FIGURE 1b); Mesopotamian figure-of-eight shaped stone borers were discovered by Woolley at Ur (Woolley 1955: 75, figure 15b) (FIGURE 1c). Circular borers were used to grind stone bowls whose interior was no wider than the mouth. A stone borer in the British Museum (BM 124498 from Ur), curved underneath and flat on top, has a piece cut out from each side of its upper surface, also for retaining a forked shaft. At Ur, stone borers were common in the Uruk and Jemdet Nasr periods, and Woolley thought that the constricted parts of these stone borers were engaged by a forked wooden shaft driven by a bow (Woolley 1955: 14) (FIGURE 2). Borers made from diorite are common to Mesopotamia and Egypt; other stones utilized in Egypt included chert, sandstone and limestone.

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Striations on Mesopotamian vessels, and the bottom surfaces of stone borers, are similar to striations seen on their Egyptian counterparts -- generally 0.25 mm wide and deep. Archaeological (e.g. BM 124498 borer from Ur; Petrie 1883: plate XIV, 7, 8; 1884: 90; Petrie Collection alabaster vase UG 18071) and my recent experimental evidence (Stocks 1988: 111--36) strongly indicate that stone borers, and copper tubes, were both employed with quartz sand abrasive.

The copper tubular drill, rotated with sand abrasive, produces a cylindrical slot round a central core, which is removed to make the full-sized hole. Stone borers, in particular the figure-of-eight shape, were mainly used to enlarge holes already made by a tubular drill. No copper tubes for drilling stone have ever been discovered in Egypt or Mesopotamia; tubes wear down during use, and the short stubs left would have been melted down as scrap. Neither the forked wooden shafts nor the tools that drove them have been discovered. However, they are illustrated in a number of Egyptian tombs constructed between Dynasties V and XXVI; there are no known representations from Mesopotamia.

In these Egyptian illustrations, the vessel obscures the lower, working end of the tool's shaft. However, during Old Kingdom times the ideogram used in words for 'craft', 'art' and other related words depicts a forked, central shaft with two weights (Gardiner 1957: 519, sign U25; Murray 1905: I, plate XXXIX, 65) (FIGURE 3a); by the New Kingdom, this ideogram had changed to a forked shaft lashed to a central shaft with one circular weight (Gardiner 1957: 518, sign U24; Davies 1943: II, plate LIV) (FIGURE 3b). From Dynasty V onwards, a forked shaft was secured to the central shaft of a tool, as seen on a representation from a Dynasty V tomb at Saqqara (Cairo Museum JE39866) and a painted Dynasty XII representation (Fitzwilliam Museum E55.1914 limestone fragment from Lahun).

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The Old Kingdom tool consisted of a straight wooden shaft, inclined at an obtuse angle near the top and tapered to a curved, blunt point; it was probably manufactured from a suitable tree branch. Two weights were fastened immediately under the inclined and tapered top part (see FIGURE 3a) to place a load upon a drill-tube or stone borer.

The tool for preliminary drilling operations would have had a copper tube force-fitted on its central shaft (FIGURE 4): some tomb illustrations may display a central shaft fitted with a tube for drilling purposes, particularly for wide-mouthed vessels; an unfinished porphyry vase (Cairo Museum JE18758) was drilled with eight adjacent holes to excavate the central mass. It is likely that the drilling tool did not change in form, except for the manner in which it was weighted; a tubular drill would not have damaged its wooden shaft during use, and new tubes could be fitted to the same shaft time and time again. The ideogram shows only the visually interesting and informative view of the forked shaft and borer, rather than a tube (cf. FIGURES 3 & 4).

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The tool was adapted for its secondary role, that of a boring implement, by lashing a forked shaft to the central shaft (see FIGURE 3b) to engage with figure-of-eight and circularshaped borers (FIGURE 5). Another type of stone borer -- an inverted truncated cone with two slots cut opposite each other in the upper, horizontal surface -- was employed to shape a vessel's mouth (uncatalogued cone, Petrie Collection, University College, London). Crescent-shaped flints, also engaged by forked shafts, were used exclusively for cutting soft stone, for example, gypsum, without sand abrasive (Caton-Thompson & Gardner 1934: 105, 130). In extended use, the forks of reconstructed tools showed wear (Stocks 1988: 168--213). A worn-out forked shaft could be replaced by lashing a new one to the central shaft, much as a drill-bit is replaced on a modern electric drill. As the destruction of a forked central shaft would render the whole tool useless, the tool may have evolved from this original configuration.

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The Twist/Reverse Twist Drill (TRTD)

Some copper drill-tubes were driven by bows, e.g. in sarcophagus manufacture in Egypt (Stocks 1988: 114--15, 144--67), but the difficulties of making stone vases with thin walls excluded this technique. I found that the mechanical stresses imposed on thin stone walls by precessional forces in bow-drilling breaks the vessel. Also, the backward-and-forward movement of a bow causes sand trapped outside the tube to enlarge the internal hole out towards the external wall of the vessel, particularly in soft stone. Drill cores produced by bow-driven tubes are tapered (Petrie 1883: plate XIV, 7), which is at variance with the archaeological evidence for stone vessel drilling. An uncatalogued Old Kingdom alabaster vase in the Petrie Collection still retains its parallel-sided core in a hole made by a tubular drill.

I found it best to twist the tool first clockwise, by approximately 90[degrees], and then anti-clockwise to its starting position. One hand grips the inclined and tapered top part, or handle; the other hand grips the central shaft, just below the weights. The curved handle fits the semi-clenched hand perfectly, and must have been chosen and carved for this purpose. In using a figure-of-eight stone borer, the craftsman must periodically change the position of his hands, in order to cut evenly around the whole circumference of a vessel. The twist/reverse twist motion produces a core with parallel sides (FIGURE 6). I have named this tool the Twist/Reverse Twist Drill, or TRTD (Stocks 1988: 178), calling it a 'drill' even though its other function was boring.

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The use of figure-of-eight shaped stone borers of different dimensions allowed gradually changing internal diameters to be ground, and the initial process of undercutting vessel shoulders. The stone borer, when employed with sand abrasive, gives so much resistance that I found it could not be rotated by a bow (as suggested by Woolley).

Experiments with stone borers

In Mesopotamia, only the stone borer has survived to indicate how Mesopotamian craftsmen made stone vessels. The figure-of-eight borer, common to both Egypt and Mesopotamia, is crucial evidence. It is only by using the Egyptian sources, and by experiment, that Mesopotamian stone vessel manufacturing techniques can be assessed.

Figure-of-eight and circular borers were tested for rotation by a bow. The figure-of-eight shaped borer usually touches a worked surface in two distinct places, either side of the forked shaft, whereas a circular borer engages with the whole of its lower surface. Dry sand abrasive was employed, as previous experience with copper tubes and stone borers (Stocks 1988: 124--32) has determined that wet sand abrasive is not efficient. The essence of drilling and boring with sand abrasive, which contains relatively large quartz crystals, is the continual replacement of worn crystals by fresh, angular ones at the cutting face. Wet sand, or wet sand dryingout, prevents this. Copper tubes can drill stone, even granite, because individual quartz crystals, which are mainly angular in shape, embed themselves into the softer copper for a fraction of a second and are swept around the stone's surface. (I found that a pressure of 1 kg/[cm.sup.2] upon a drill-tube's cutting face is optimum.) Stone borers also engage quartz crystals, but not so well.

Very wet, or fluid, sand will interchange, but is unsuitable for other reasons. The sand, when ground, turns into a fine powder, with the texture of flour. This powder packs inside a tubular drill and, even when perfectly dry, sticks together in one mass and remains inside the tube when it is removed from a hole. In this way, the powder from dry sand can be withdrawn from deep, tubular holes drilled into a sarcophagus (essentially a giant stone vessel), whereas wet powder cannot. Egyptian and Mesopotamian craftsmen must have discovered these properties of sand for themselves.

After experimenting with different powders obtained from drilling both hard and soft stone by copper tubes, I propose that ancient craftsmen employed these by-products for drilling stone beads, polishing stone artefacts and creating faience cores and glazes (Stocks 1988: 127--8, 235, 261--4; 1989a: 528; 1989b: 21--6). A stiff paste can be made by adding sodium bicarbonate (natron in ancient times) and water to the powder obtained from drilling soft stone -- limestone or calcite (Egyptian alabaster). Moulded or modelled into any shape and fired at 850[degrees]C, it becomes a stable, hard, whitish material, speckled with blue spots from particles of copper worn off the drill-tube. Glazed with a runny paste, made with powder derived from drilling hard stone, for example, rose granite and diorite, and fired again at 800[degrees]C, turned the glaze blue. These core and glaze materials are similar to Egyptian faience in appearance. A scanning electron micrograph (SEM) shows that the powdered material contains many particles within the size range of 0.5--5 microns (FIGURE 7), particularly in hard stone powder. Breathing these fine particles causes lung damage to craftsmen (Stocks 1988: 127, 204--5; Curry et al. 1986: 58--9, figure 2).

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Each test borer was admitted into a previously prepared hole, which imitated the interior of a partly bored vessel (Stocks 1988: 189). A forked shaft was engaged with each borer. A stone bearing fitted the top of the shaft, turned by a bow. The figure-of-eight borer jammed in the hole and caused the bow-string to slip on the shaft. The reason was the result of an out-of-balance centrifugal force acting upon the end of the borer swinging away from the operator. Similar jamming occurred with the circular borer. Even if a borer could be rotated by a bow, sand-induced friction is so high that constantly to overcome it creates unacceptable stresses. The experiments do not support the driving of Mesopotamian borers by bow-driven forked shafts.

Experimental manufacture of a stone vessel

In order to test whether the TRTD could be used to make a stone vessel, a small, barrelshaped vase (FIGURE 8) was first shaped from soft limestone by copper chisels and adzes, flint punches, chisels and scrapers and sandstone rubbers. It was excavated by two copper tubes, and stone borers (Stocks 1988: 192--212). After shaping, the vase was separately drilled by each tube, one within the other, so as to weaken the core. The eyes in some ancient statuary were made this way, and a tubular core that was formed by two tubular drills employed in this fashion was found by W.M.F. Petrie (Petrie 1917: plate LII, 61). The drills were located by chipping and scraping circular grooves that matched each drill's diameter. (An uncatalogued alabaster vessel in the Petrie Collection has a similar groove in its top surface.) I used flint punches, chisels and scrapers to create these grooves, and the tools were also found to be effective for granite and diorite. Ancient vessels and hieroglyphs in hard stone were probably shaped and cut by these types of flint tools (Stocks 1988: 246--73).

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The drilling took five hours to complete. As soon as a core filled the hollow drill, it was carefully broken off by copper chisel and mallet; this technology allowed ancient drill-tubes to reach to the bottom of deep vessels, and explains why TRTD stone weights were placed high up the shaft. Boring the hole to match the bulbous exterior, by figure-of-eight stone borers, occupied another 10 hours. At any particular point of enlargement, a borer that was slightly longer than the existing internal diameter was selected for use. A borer entered the vessel vertically, and was then turned horizontal; sand was poured into the vase, level with the borer. A forked shaft could now be engaged with the borer. It took an hour to undercut the vase's shoulders by hand-held, hook-shaped flint scrapers, and hook-shaped stone borers, used with sand abrasive.

Tests to drill rose granite and diorite, by a copper tube, showed that these stones took 15 times longer to drill than limestone (Stocks 1988: 212, 340). A granite, barrel-shaped vessel, of similar dimensions to the limestone vase, would take me 75 hours to excavate by drill-tube, although experienced ancient craftsmen would have bettered my cutting rates in both stones. Some test results, which record ratios of copper lost from drill-tubes to excavation depths in stone, and excavation rates, were obtained from drilling granite, diorite, calcite and soft limestone by bow-driven and twist/reverse twist driven copper tubes (TABLE 1).
material ratio: bow-driven twist/reverse
 copper to rate (cubic twist rate (cubic
 stone cm per hour) cm per hour)
granite 1:3 2 0.4
diorite 1:3 2 0.4
calcite 1:>100 30 6
limestone 1:>100 30 6


Conclusions

It is apparent that ancient Mesopotamian and Egyptian stone vessel craftsmen must have adopted the twist/reverse twist manner of driving their tubular drills and stone borers.

Egyptian representations of the tool show its extreme simplicity of form; nowhere in Egyptian representations of stone vessel production does the ancient artist ever display a stone borer being driven by a bow. Tomb artists never showed a tubular drill being driven by a bow, although the use of bow-driven tubes must have been well known. The experiments demonstrate that the twist/reverse twist technique provided the only satisfactory method any ancient stone vessel craftsman could have employed for driving tubular drills and stone borers. The figure-of-eight borer can only be driven with the leverage and control of the Twist/Reverse Twist Drill, and the finding of such borers in Mesopotamia indicates the use of some form of this tool.

Acknowledgement. I am indebted to Peter Clayton for reading a preliminary manuscript and suggesting some useful amendments to the text. However, the ideas expressed here are entirely the responsibility of the author.

References

CATON-THOMPSON, G. & E.W. GARDNER. 1934. The desert Fayum. London: The Royal Anthropological Institute of Great Britain and Ireland.

CURRY, A., C. ANFIELD & E. TAPP. 1986. The use of the electron microscope in the study of palaeopathology, in A.R. David (ed.), Science in Egyptology: 57--60. Manchester: Manchester University Press.

DAVIES, N. DE G. 1943. The tomb of Rekh-mi-Re at Thebes. New York (NY): Metropolitan Museum of Art. Publication of the Metropolitan Museum of Art Egyptian Expedition XI.

GARDINER, A.H. 1957. Egyptian grammar. 3rd edition. Oxford: Griffith Institute, Ashmolean Museum.

HOFFMAN, M.A. 1980 Egypt before the pharaohs. London: Routledge & Kegan Paul.

LUCAS, A. 1962. Ancient Egyptian materials and industries. Revised by J.R. Harris. 4th edition. London: Edward Arnold.

MOOREY, P.R.S. 1985. Materials and manufacture in ancient Mesopotamia: the evidence of archaeology and art, metals and metalwork, glazed materials and glass. Oxford: British Archaeological Reports. International series S237.

MURRAY, M.A. 1905. Saqqara mastabas. Part I. London: Egyptian Research Account. Number 10.

PETRIE, W.M.F. 1883. The pyramids and temples of Gizeh. London: Field & Tuer.

1884. On the mechanical methods of the ancient Egyptians, Journal of the Anthropological Institute 13: 88--109.

1917. Tools and weapons. London: British School of Archaeology in Egypt.

QUIBELL, J.E. & F.W. GREEN. 1902. Hierakonpolis. Part II. London: Quaritch. British School of Archaeology in Egypt Memoir 5.

REISNER, G.A. 1931. Mycerinus, the temples of the third pyramid at Giza. Cambridge (MA): Harvard University Press.

STOCKS, D.A. 1988. Industrial technology at Kahun and Gurob: experimental manufacture and test of replica and reconstructed tools with indicated uses and effects upon artefact production. Unpublished MPhil. thesis, University of Manchester.

1989a. Ancient factory mass-production techniques: indications of large-scale stone bead manufacture during the Egyptian New Kingdom Period, Antiquity 63: 526--31.

1989b. Indications of ancient Egyptian industrial interdependence, Manchester Archaeological Bulletin 4: 21--6.

WOOLLEY, C.L. 1934. Ur excavations II. London: The Trustees of the British Museum and the Museum of the University of Pennsylvania, Philadelphia.

1955. Ur excavations IV. London: The Trustees of the British Museum and the Museum of the University of Pennsylvania, Philadelphia.
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Author:Stocks, Denys A.
Publication:Antiquity
Date:Sep 1, 1993
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