Experiments in Egyptian Archaeology: Stoneworking Technology in Ancient Egypt

Categorie Livre 1
Categorie Livre 2
Date
2003
Pages
296
Auteur (s)
Online





Description - Livre

In this fresh and engaging volume, Denys A. Stocks examines the archaeological and pictorial evidence for masonry in ancient Egypt. Through a series of experiments in which he tests and evaluates over two hundred reconstructed and replica tools, he brings alive the methods and practices of ancient Egyptian craftworking, highlighting the innovations and advances made by this remarkable civilisation.

This practical approach to understanding the fundamentals of ancient Egyptian stoneworking shows the evolution of tools and techniques, and how these come together to produce the wonders of Egyptian art and architecture.

Comprehensively illustrated with over two hundred photographs and drawings, Experiments in Egyptian Archaeology will bring a fresh perspective to the puzzles of Egyptian craft and technology. By combining the knowledge of a modern engineer with the approach of an archaeologist and historian, Denys Stocks has created a work that will capture the imagination of all Egyptology scholars and enthusiasts






Détails - Livre

1. Flinders Petrie propose que les Egyptiens abrasait les roches dur avec du Cuivre avec du diamants, béryl et corindon
Sable proposé 

1. Grosse amélioration durant l'ère Predynastic

2. Nagada I period (ca. 4000–3600 BC) vessels made of hard and soft stones, such as basalt, granite, calcite, gypsum and limestone, were produced in increasing numbers.

2. The rapid expansion of hard stone vessel production in the Nagada II, (ca. 3600–3200 BC) period indicates that new, faster and reliable vessel manufacturing methods were introduced during this time.

2. Several important areas of ancient technology remain shrouded in mystery, particularly those concerned with stoneworking: our ability to assess the development of ancient Egyptian technology, despite finding many tools, artifacts and tomb illustrations of manufacturing processes, is frustrated by an incomplete knowledge of important crafts, and virtually no knowledge at all of significant tools missing from the archaeological record.

2. The precise construction and use of the stone vessel drilling and boring tool is only partly perceived, and none of the New Kingdom period mass-production equipment for drilling stone beads, a development of the single bead drill, has survived.

2. We do not know, with reasonable certainty, how particular materials were worked in any given situation: tools’ cutting and wear rates need to be established for a range of materials. The precise construction and use of the stone vessel drilling and boring tool is only partly perceived, and none of the New Kingdom period mass-production equipment for drilling stone beads, a development of the single bead drill, has survived. Only some illustrations in six New Kingdom tombs3 at Thebes indicate the existence of an important and systematic drilling procedure. The constructional methods and tools for making sarcophagi and statuary in hard stone, the close fitting of the stone blocks used for architecture, the source of the frit and the faience core and glaze materials, and the cutting of incised and low reliefs, and of hieroglyphs, in hard and soft stone are also incompletely understood.

8. Bronowski’s comments usefully illuminate the change from Early Dynastic mud brick architecture to buildings made from stone blocks shaped with cutting tools: the prime example is the construction of the Step Pyramid at Saqqara (Figure 1.1).

11. The working of the hard stones, such as quartzite, basalt, granite, chalcedony and schist, predated the introduction of edged copper tools. However, even if Merimden craftworkers had possessed sharpened copper chisels, the experiments with copper, bronze, and even iron chisels, demonstrated their total inability to cut certain hard stones, particularly the igneous types. The necessary techniques and stone tools for working the hardest stones continued to be developed throughout the Predynastic period, enabling Dynastic craftworkers not only to shape the hard stones into statuary, obelisks, sarcophagi, and a multitude of other artifacts, but to incise hieroglyphs and reliefs into them.

15. Some of the research for this book closely examines the abilities of various tools to work different stones. Wherever clarification and emphasis is needed, stones are provided with their Mohs hardness numbers,26 but there is a summary of a crosssection of the stones in use for buildings, vessels, beads, statuary, obelisks and other artifacts in Table 1.1. The stones are placed into two groups: Mohs 3, and below, and above Mohs 3.

16. Although the manufacture of stone vessels commenced during the Predynastic period, the first illustrations of the process are to be seen in two Fifth Dynasty tombs at Saqqara;29 the last illustration occurs in the Twenty-sixth Dynasty tomb of Aba at Thebes.30 The earliest representation of the stone vessel maker’s drilling/boring tool, the ideogram used in words connected with ‘art’, ‘craft’, and in other words, dates to the Third Dynasty at Saqqara.31 Among the stones worked into vessels were basalt, breccia, calcite, diorite, granite, greywacke, gypsum,32 limestone, marble, porphyry, serpentine and steatite.33 Toward the end of the Old Kingdom, the number of stone vessels decreased considerably, with most of the harder stones going out of use.34 However, the manufacture of stone vessels continued until the end of Egyptian civilization, a large proportion of them being made from calcite, a relatively soft stone compared with granite or diorite.35

18. A number of ancient tools, and their uses, are familiar today. The shapes of the present chisel, adze and axe remain unchanged, but the metals employed to make them have altered. Modern cutting tools are made from carbon steel, but in ancient times copper, followed by bronze and iron, were the metals in use. Although tools of copper increasingly supplemented the use of sharp-edged flint tools as the Neolithic period ended ca. 4000 BC, the employment of flint for tools continued at least until the Twenty-fifth Dynasty.3

19. Some tools have been located by archaeologists at different sites in Egypt, but various tool marks on artifacts, together with tomb depictions of working techniques, indicate that key industrial tools are unknown.

19. Tomb artists never recorded certain important techniques, one of them being the manufacture of the sarcophagus from a single block of stone. Furthermore, all of the functions of the tools we do possess may not be known, obscuring our understanding of ancient technology. This lack of information of manufacturing methods also conceals the manner in which ancient workers organized their work.

21. The replica cutting tools were tested for hardness before and after hammering into shape; after test, their life expectancy was calculated. Some experimental specimens of copper and bronze were hardness-tested by J.R. Maréchal.51 However, replica copper and bronze alloy chisels, forming a series containing different constituent metals, or increasing percentages of them, have never been tested for hardness, and used on various materials to establish relationships between chisels’ hardnesses and their cutting capabilities.

Although it is selfevident what a chisel does, certainty of its precise ancient use upon different materials cannot be stated with complete confidence. Therefore, copper and bronze chisels were thoroughly investigated. Similarly, without using a replica of the surface testing tool there is insufficient information from the tomb illustrations to be certain of all its ancient applications. Where tools are known only from tomb illustrations their construction and uses are even more perplexing.

21. Three particular craft strategies are still practised today. These are metal casting, the hand grinding of tools and artifacts using abrasive stones and/or a loose abrasive powder, and the scraping of metal by harder metal scrapers.

27. Egyptian copper chisels developed into two basic shapes, the ‘flat’ and the ‘crosscut’, which are still in use today (Figure 2.3). The flat copper chisel, for working soft stone, was hammered into a wide, double tapering section, ending in an edge sharpened from both sides; sometimes, like a modern woodcutting chisel, a single slope ended in an edge.11 The flat chisel was useful for quickly removing large areas of wood and soft stone, where a perfectly flat and smooth surface was not initially important. To make the crosscut chisel,12 a copper bar was initially hammered into a double taper, but was then turned through 90° and hammered into a second, narrower double taper. This chisel’s shorter edge concentrated a blow upon a smaller cutting area; the Egyptian woodworker employed the crosscut chisel’s superior strength to cut and lever wood from deep mortises (Figure 2.4). The flat chisel’s edge operated on materials in a similar fashion to the adze blade. However, the twin advantages a chisel has over an adze are the craftworker’s ability to direct the blade to an exact position on the workpiece, before a blow is struck, and also to vary the chisel’s angle of attack from an acute angle to the workpiece through to a vertical position, which enables the tool to split materials like an axe blade.

31. Two other cutting edges deserving a high ranking in the pecking order of craftworkers’ implements are serrated and flat-edged copper saws (see Figure 2.1). It is important that a distinction between saws with and without serrations is made at this stage. The earliest located serrated saws for cutting wood, and possibly for cutting soft stone, date to the Third Dynasty;23 in addition to a model saw from this dynasty, a notched copper saw was found at Meidum.24 It is likely, however, that the serrated saw originated even earlier than the First Dynasty, when it was employed for sawing wood for coffins. Saws were sometimes hammered with tangs, for fitting curved wooden handles, although in at least one Fifth Dynasty saw the handle was hammered from the same sheet of copper forming the blade.25 The crudest saw was a blade notched by chopping it on a sharp object.26 Other serrations may have been produced by sharp-edged sandstone rubbers. The technology for producing thin-bladed saws is linked to the casting of copper plates directly into open sand or pottery moulds and hammering the cooled casting into thinner sheets.

32. Evidence for the flat-edged copper saw for cutting hard stone is connected, in part, with slots and saw marks found on stone sarcophagi and other stone objects. For example, the Third Dynasty calcite sarcophagus of Sekhemkhet and the Fourth Dynasty rose granite sarcophagus of Khufu were sawn to shape.27 Some slots have been connected by archaeological evidence to the use of copper,28 but recent experiments with hard stone29 have incontrovertibly shown that serrated copper, bronze, or indeed iron and steel, saws could not possibly have cut such an unyielding material. A fuller appraisal of the flat-edged saw type, and its working method, will be discussed in Chapter 4, but all that needs to be said at present is that the casting of a plate of copper in an open mould was also utilized for manufacturing flat-edged, stonecutting saws, in addition to serrated woodcutting saws.

32. Ancient Egyptian craftworkers also employed two types of edged metal tools for drilling materials, and these were the bow-driven copper wood drill for drilling holes in furniture30 and the bow-driven, and also directly hand-operated, flatended copper tubular drill.31 This tube was employed for drilling not only deep holes in stone, but also shallow, tubular-shaped slots. An example of this practice, thought to be decorative, is a diorite bowl (MM 10959) belonging to Khaba of the Third Dynasty, which was supplied with a truly circular groove cut into the central section of the interior bottom surface.

32. Hard stone vessel manufacture accelerated during the Nagada II period, owing its expansion to the increased employment of the copper tubular drill for the initial hollowing of vessels’ interiors. The First and Second Dynasties saw the continuation of hard stone vessel production and, subsequently, in the Third and Fourth Dynasties, the tube was additionally in use for the hollowing of calcite and harder stone sarcophagi.

33. The bow-driven copper wood drill, illustrated in several tomb scenes,32 was in use for making rows of holes in chairs and beds for anchoring supporting lattices of leather thong or cord (Figure 2.12). In the tomb of Rekhmire at Thebes,33 both uses are illustrated. The wood drill was also used for piercing a woodworking joint to admit dowels (wooden pins) for securing and strengthening it.34 To rotate a wood drill, a bow’s string was given a single turn around a wooden shaft into which the drill was tightly fitted. The top of the shaft was rounded to fit snugly into a lubricated hemispherical-shaped bearing hole, which was chipped and smoothed into the underside of a capstone. The lubricant was possibly tallow. Ancient wood drills could be shaped like a slim, flat chisel (e.g. BM 6042–3). However, other drill blades were probably formed by beating the metal into a flat taper and then shaping it like an arrowhead35 Two wood drills were made for test (Figure 2.13), one with a sharpened, flat chisel-edge, the other supplied with an arrowhead-shaped cutting point. No Predynastic drills for perforating wood have ever been discovered.36

42. In the Twelfth Dynasty, four large copper boxes were cast in closed moulds. They were excavated at Tôd in Upper Egypt by F. Bisson de la Roque.68 One of the boxes weighs 37.5 kg and its walls are 1 cm thick. It is likely that between 25 and 30 large crucibles of copper were needed to cast this box in a single operation, and it is abundantly clear that the use of multiple numbers of furnaces was normal in the Middle and New Kingdom periods.

42. The archaeological evidence for the employment of large diameter copper tubular drills and long copper saws, from the Third Dynasty onward, for the drilling and sawing of calcite and granite sarcophagi indicates that ancient stonecutting tubes and saws, particularly the saws, required a considerable amount of copper to make a single tool.

42. The longest saws probably required up to 20 kg of copper (e.g. for cutting Khufu’s granite sarcophagus to shape), the largest known diameter tube for sarcophagus manufacture (Khufu’s 11 cm-diameter tube – see Chapter 4) possibly needing between 2–4 kg of copper, depending upon the tube’s wall thickness which, for Khufu’s sarcophagus drill-tube, will always remain unknown.

43. The hammering of copper and bronze for both shaping and hardening these metals became an established craft after the introduction of copper casting at the commencement of the Nagada II period. In particular, copper, and later bronze, cutting tools were necessarily hammered in the cold state to achieve maximum hardness.70 Tongs are not depicted in tomb scenes until the Eighteenth Dynasty tomb of Rekhmire,71 but it is unlikely that these were ever used for holding hot copper and bronze tools during the hammering process. To illustrate that tongs were unnecessary for this purpose, a bronze bar (95 per cent copper, 5 per cent tin) was raised to a bright red heat and immediately hammered. Within several seconds, the metal fractured into several pieces. Red-hot copper and bronze become brittle because of changes in their crystal structures, which occur at elevated temperatures.72 However, after a period of cold hammering copper alloys need to be annealed (softened) by reheating to a dull red colour and allowing them to cool slowly. This restores a metal’s malleability and delays cracks in the metal caused by excessive hammering.

46. The elbow, in conjunction with the lower arm’s ability to twist through nearly 180°, while the upper arm remains stationary, allows humans consistently to apply downward blows that instantly can be varied in weight, frequency and direction; both the lightest, and the heaviest, blows necessary for delicate work on gold vessels, jewellery and leaf, and for fashioning metal tools, can be monitored closely by the eye and the brain, whereas a hammer’s head fitted with a handle can easily be misdirected.

56. The project furnace for casting coppers and bronzes into open sand moulds was constructed from sheet metal riveted together to form a hood, a flue and a base, which contained a lining of firebricks (Figure 2.48). This lining formed a space for the fuel equal in volume to the average capacity of the ancient furnaces examined by Rothenberg at Timna in the Negev desert. When fully filled with fuel, a bowl-shaped furnace measuring 30 cm in height and 25 cm in diameter was created. An electric blower supplied air through a steel pipe connected to the furnace. The air flow rate could be adjusted from a minimum of 200 l/minute to a maximum of 600 l/minute (Figure 2.49). The maximum flow rate allowed the furnace to reach an operating temperature of approximately 1,500°C, the minimum flow rate producing a temperature somewhat in excess of 1,200°C. Three modern silicon carbide crucibles were available for use.

63. The stonecutting tests103 were performed with copper, leaded bronze and bronze crosscut and flat-tapered chisels, a modern flat-tapered steel chisel and a steel punch, copper adze blades and the serrated copper saw blades. The stones utilized for test included two sedimentary types (red sandstone and soft limestone), a close-grained hard sandstone, together with hard limestone, calcite, rose granite and diorite.

63. Several copper, bronze and leaded bronze chisels were tested upon rose granite and diorite. Each chisel suffered severe damage to its cutting edge. The damage inflicted upon ancient iron chisels by using them to cut igneous stones was considered. To test this proposition, a hardened and tempered engineer’s steel chisel (VPN 800), together with a hardened steel punch (VPN 800), was employed to cut a groove 0.5 mm deep into a smoothed surface on a block of diorite. The tools suffered severe damage, similar to the non-ferrous chisels.

64. No worker would tolerate such a state of affairs, where a valuable tool received severe damage without a commensurate return in work performance. In any event, ancient Egyptian masons had easy access to cheap and plentiful supplies of a material suitable for the working of hard stones, namely flint.

64. Consequently, even the hardest ancient bronze chisels must have lost metal at a rate that could not have been acceptable to ancient workers. All of the chisels cut red sandstone and soft limestone with ease, although the softer chisels suffered slight wear over time.

64. Tests with the steel chisel upon close-grained hard sandstone indicated that this stone type, quarried at Gebel Silsila for making blocks, particularly for the Graeco-Roman temples at Philae, Kom Ombo, Edfu, Esna and Dendera, could have been cut with ancient iron chisels. In order to test some realistic working procedures, a bas-relief of the uas-sceptre and one of the ankh symbol were carved into a soft limestone (Figures 2.54, 2.55), similar to that used to face the Great Pyramid, with copper and bronze chisels.

65. Petrie made a useful observation with regard to marks left by metallic and flint-cutting tools. He remarked that the adze was used in the chamber of Kho-sekhemui (Second Dynasty), but that the blade was of flint, this revealed by the chips on the tool’s edge leaving raised ridges on the stone, whereas a metal tool has jagged dents on the edge which leaves score marks on the stone facing.106 The tests on limestone with copper, bronze and flint tools fully support these observations.

67. The thin replica saws proved to be efficient when tested on red sandstone and soft limestone, and it is known that ancient sawyers discovered this use for serrated copper saws.108 Flat-edged, stonecutting saws can cut both soft and hard stone, but serrated saws are able only to cut red sandstone, soft limestone, gypsum and steatite; the rate of cutting is remarkably swift. 

69. The test cutting of hard and soft wood with copper and bronze chisels, saws, adzes, an axe, and a bow-driven wood drill, indicates that ancient copper and bronze tools possessed such superior hardness over all woods that only infrequent sharpening was necessary. The replica bow-driven wood drills, when rapidly revolved, both achieved cutting rates in softwood of 66 cm3/hour, whereas holes in hardwood, such as oak and mahogany, were drilled at the rates of 20 and 30 cm3/hour respectively.

69. In conclusion, the tests proved that no copper, bronze or leaded bronze tool, except for the tubes and the flat-edged saws with sand abrasive, could effectively cut stone other than red sandstone, soft limestone, gypsum and steatite, and that all of the tools used for cutting woods of all hardnesses were practical for this purpose. Only stones of hardness Mohs 3, and below, can effectively be cut with any copper, bronze or leaded bronze edged tool. The tests with the modern steel chisel and punch indicate that Late Period craftworkers did not employ their softer iron chisels for cutting hieroglyphs and reliefs into granite, diorite, porphyry and other stones of similar hardness.

74. Much discussion has taken place as to how ancient Egyptian artisans worked the hard stones. These included granite, basalt, diorite, porphyry and quartzite (all igneous stones of hardness Mohs 7, except for quartzite, Mohs 6–7, the Egyptian variety being a sedimentary stone, not the normally metamorphic type). The experiments evaluated in Chapter 2 indicated that even calcite, a relatively ‘soft’ stone of hardness Mohs 3–4, cannot efficiently be cut with copper alloy tools. In particular, the cutting of bas and incised reliefs and hieroglyphs into the hard stones (Figure 3.1), together with the fashioning of hard stone vase exteriors and sculptures, have been the subject of much speculation. It is also apparent that other technical practices owed their development to the existence of a hard tool material that could be given exceptionally sharp edges; the engraving of copper is an example. The main intention of this chapter is to demonstrate how these stonecutting, carving and engraving functions could have been accomplished by the manufacture and employment of particular stone tools. The tremendous amount of ancient hard stone working required a tool material that was plentiful and very hard, and yet tough enough to withstand to some degree the stresses imposed upon it, even though by definition a very hard substance is likely to be brittle.

81. Often, pitting of a stone’s surface may be seen in the bottoms of hieroglyphs incised into various types of stone. This pitting, caused by a pointed punch, is normally scraped to a flat finish. However, two sarcophagi in the Musée du Louvre, Paris, illustrate the difficulties inherent in this procedure. Both sarcophagi have hundreds of small, incised hieroglyphs on their inside surfaces. In sarcophagus N345 D9, made from greywacke, the bottoms and sides of the incised signs have been scraped to a flat finish.

81. Although copper began to supplement flint tools as the Neolithic period ended, ca. 4000 BC, flint remained in use as a tool-manufacturing material throughout the Predynastic period, and most of the Dynastic era. However, flint and chert sharp-edged tools gradually declined in numbers and quality during the Dynastic period, more or less ending as the technological processes for making wrought iron into quenched and tempered steel became established in the seventh century BC. 31 Even after this date, though, flint and chert chisels and punches must have been produced for working the very hard stones.

81. Certain hard stones have been considered as candidates for ancient tool manufacture. These are obsidian, dolerite and diorite. However, obsidian was an imported volcanic glass-like stone. Its scarcity and extremely brittle nature excludes it from further consideration. Although dolerite, a coarse-grained basalt, was useful for pounding other hard stones, fragments of dolerite, and chisels of diorite, have been tested by Antoine Zuber32 and by Reginald Engelbach33 to cut granite. However, as tool materials they both suffer from an inability effectively and decisively to cut into the hard stones.

81. Flint is a dense form of silica, being dark grey or black in colour (see Figure 3.6).37 Although flint’s hardness is classed as Mohs 7, tests38 show that it is slightly harder than quartz, also Mohs 7. Flint occurs as nodules and layers in the Eocene limestone, and also can freely be picked off the ground where weathering has released them. Flint nodules assume quite convoluted shapes, being originally formed from the silica skeletons of dead sponges that lived in the shallow sea covering part of Egypt some 50 million years ago.39 These skeletons were deposited on the sea’s embryonic limestone floor, among the millions of small marine creatures from which this sedimentary rock is composed. The silica skeletons dissolved, and this material was later deposited as flint nodules, which individually occupied spaces in the limestone. The most southerly source of flint is in the mountains of Thebes West, but excellent quality flint was mined at the Wadi el-Sheikh and the Wadi Sojoor, both about 130 km south of Cairo, and in the eastern environs of the Nile valley.

86. It is likely that some eye damage could also have been caused by flying flints in ancient times. A flint punch, or chisel, knapped to a flat striking surface, like the Kahun punches, could have been driven with a stone hammer into soft and hard stones, especially for fine carving purposes. But awkwardly shaped flint tools invite the use of a wooden mallet for driving them. Wood absorbs some of the impact, and any flint splinters penetrate the wood and, later, fall harmlessly to the ground as the mallet’s surface becomes eroded.

91. The experimental granite-working results indicate that ancient artisans could have chiselled and punched rose granite at the rate of approximately 15 cm3/hour, or about three times the experimental rate. The explanation for this disparity is connected to the experimental conditions. First, the relatively small test pieces of granite rebounded when struck with the chisel, and this phenomenon counteracted some of the shock of a blow. As a result, a chisel’s edge did not penetrate to its maximum possible amount. Conversely, large granite blocks, by virtue of their mass, assist the transmission of the blow into the stone. Second, the necessarily smaller flint tools, and consequentially lighter tool blows, employed on these relatively small pieces of granite. At the anticipated ancient stone removal rate of 15 cm3/hour, a granite column nb hieroglyph could have been chipped out in eight hours.

91. The experimental granite-working results indicate that ancient artisans could have chiselled and punched rose granite at the rate of approximately 15 cm3/hour, or about three times the experimental rate. The explanation for this disparity is connected to the experimental conditions. First, the relatively small test pieces of granite rebounded when struck with the chisel, and this phenomenon counteracted some of the shock of a blow. As a result, a chisel’s edge did not penetrate to its maximum possible amount. Conversely, large granite blocks, by virtue of their mass, assist the transmission of the blow into the stone. Second, the necessarily smaller flint tools, and consequentially lighter tool blows, employed on these relatively small pieces of granite. At the anticipated ancient stone removal rate of 15 cm3/hour, a granite column nb hieroglyph could have been chipped out in eight hours.