Chap. 19. Mechanical Methods of the Pyramid Builders
Pages 173 - 177
129. [p. 173] The methods employed by the Egyptians in cutting the hard stones which they so frequently worked, have long remained in doubt. Various suggestions have been made, some very impracticable; but no actual proofs of the tools employed, or the manner of using them, has been obtained. From the examples of work which I was able to collect at Gizeh, and from various fixed objects of which I took casts, the questions so often asked seem now to be solved.
The typical method of working hard stones, — such as granite, diorite, basalt, &c., — was by means of bronze tools; these were set with cutting points, far harder than the quartz which was operated on. The material of these cutting points is yet undetermined; but only five substances are possible: beryl, topaz, chrysoberyl, corundum or sapphire, and diamond. The character of the work would certainly seem to point to diamond as being the cutting jewel; and only the considerations of its rarity in general, and its absence from Egypt, interfere with this conclusion, and render the tough uncrystallized corundum the more likely material.
Many nations, both savage and civilized, are in the habit of cutting hard materials by means of a soft substance (as copper, wood, horn, &c.), with a hard powder supplied to it; the powder sticks in the basis employed, and this being scraped over the stone to be cut, so wears it away. It is therefore very readily assumed by many persons (as I myself did at first) that this method must necessarily have been also used by the Egyptians; and that it would suffice to produce all the examples now collected. Such, however, is far from being the case; though no doubt in alabaster, and other soft stones, this method was used.
That the Egyptians were acquainted with a cutting jewel far harder than quartz, and that they used this jewel as a sharp-pointed graver, is put beyond doubt by the diorite bowls with inscriptions of the fourth dynasty, of which I found fragments at Gizeh. These hieroglyphs are incised, with a very free-cutting point; they are not scraped nor ground out, but are ploughed through the diorite, with rough edges to the line. As the lines are only 1/150 inch wide (the figures being about .2 long), it is evident that the cutting point must have been [p. 174] much harder than quartz; and tough enough not to splinter when so fine an edge was being employed, probably only 1/200 inch wide. Parallel lines are graved only 1/30 inch apart from centre to centre.
We therefore need have no hesitation in allowing that the graving out of lines in hard stones by jewel points, was a well-known art. And when we find on the surfaces of the saw-cuts in diorite, grooves as deep as 1/100 inch, it appears far more likely that such were produced by fixed jewel points in the saw, than by any fortuitous rubbing about of a loose powder. And when, further, it is seen that these deep grooves are almost always regular and uniform in depth, and equidistant, their production by the successive cuts of the jewel-teeth of a saw appears to be beyond question. The best examples of equidistance are the specimens of basalt No.4 (Pl. xiv.), and of diorite No.12; in these the fluctuations are no more than such as always occur in the use of a saw by hand-power, whether worked in wood or in soft stone.
On the granite core, broken from a drill-hole (No.7), other features appear, which also can only be explained by the use of fixed jewel points. Firstly, the grooves which run around it form a regular spiral, with no more interruption or waviness than is necessarily produced by the variations in the component crystals; this spiral is truly symmetrical with the axis of the core. In one part a groove can be traced, with scarcely an interruption, for a length of four turns. Secondly, the grooves are as deep in the quartz as in the adjacent felspar, and even rather deeper. If these were in any way produced by loose powder, they would be shallower in the harder substance — quartz; whereas a fixed jewel point would be compelled to plough to the same depth in all the components; and further, inasmuch as the quartz stands out slightly beyond the felspar (owing to the latter being worn by general rubbing), the groove was thus left even less in depth on the felspar than on the quartz. Thus, even if specimens with similarly deep grooves could be produced by a loose powder, the special features of this core would still show that fixed cutting points were the means here employed.
That the blades of the saws were of bronze, we know from the green staining on the sides of saw cuts, and on grains of sand left in a saw cut.
The forms of the tools were straight saws, circular saws, tubular drills, and lathes.
130. The straight saws varied from .03 to .2 inch thick, according to the work; the largest were 8 feet or more in length, as the cuts run lengthways on the Great Pyramid coffer, which is 7 feet 6 in. long. The examples of saw cuts figured in Pl. xiv. are as follow. No. 1, from the end of the Great Pyramid coffer of granite, showing where the saw cut was run too deep into the stuff twice over, and backed out again. No.2, a piece of syenite, picked up at Memphis; showing cuts on four faces of it, and the breadth of the saw by a cut across the top of it. This probably was a waste piece from cutting out a statue in the rough. No.3, a [p. 175] piece of basalt, showing a saw cut run askew, and abandoned, with the sawing dust and sand left in it; a fragment from the sawing of the great basalt pavement on the East of the Great Pyramid. No.4, another piece from the same pavement, showing regular and well-defined lines. No.5, a slice of basalt from the same place, sawn on both sides, and nearly sawn in two. No.6, a slice of diorite bearing equidistant and regular grooves of circular arcs, parallel to one another; these grooves have been nearly polished out by crossed grinding, but still are visible. The only feasible explanation of this piece is that it was produced by a circular saw. The main examples of sawing at Gizeh are the blocks of the great basalt pavement, and the coffers of the Great, Second, and Third Pyramids, the latter, unhappily, now lost.
131. Next the Egyptians adapted their sawing principle into. a circular, instead of a rectilinear form, curving the blade round into a tube, which drilled out a circular groove by its rotation; thus, by breaking away the cores left in the middle of such grooves, they were able to hollow out large holes with a minimum of labour. These tubular drills vary from 1/4 inch to 5 inches diameter, and from 1/30 to 1/5 inch thick. The smallest hole yet found in granite is 2 inches diameter, all the lesser holes being in limestone or alabaster, which was probably worked merely with tube and sand. A peculiar feature of these cores is that they are always tapered, and the holes are always enlarged towards the top. In the soft stones cut merely with loose powder, such a result would naturally be produced simply by the dead weight on the drill head, which forced it into the stone, not being truly balanced, and so always pulling the drill over to one side; as it rotated this would grind off material from both the core and the hole. But in the granite core, No.7, such an explanation is insufficient, since the deep cutting grooves are scored out quite as strongly in the tapered end as elsewhere; and if the taper was merely produced by rubbing of powder, they would have been polished away, and certainly could not be equally deep in quartz as in felspar. Hence we are driven to the conclusion that auxiliary cutting points were inserted along the side, as well as around the edge of the tube drill; as no granite or diorite cores are known under two inches diameter, there would be no impossibility in setting such stones, working either through a hole in the opposite side of the drill, or by setting a stone in a hole cut through the drill, and leaving it to project both inside and outside the tube. Then a preponderance of the top weight to any side would tilt the drill so as to wear down the groove wider and wider, and thus enable the drill and the dust to be the more easily withdrawn from the groove. The examples of tube drilling on Pl.xiv. are as follow:— No. 7, core in granite, found at Gizeh. No.8, section of cast of a pivot hole in a lintel of the granite temple at Gizeh; here the core, being of tough homblende, could not be entirely broken out, and remains to a length of .8 inch. No.9, alabaster mortar, broken in course of manufacture, showing [p. 176] the core in place; found at Kom Ahmar (lat. 28º 5'), by Prof. Sayce, who kindly gave it to me to illustrate this subject. No. 10, the smallest core yet known, in alabaster; found with others at Memphis, by Dr. Grant Bey, who kindly gave me this. No. 11, marble eye for inlaying, with two tube drill-holes, one within the other; showing the thickness of the small drills. No.12, part of the side of a drill-hole in diorite, from Gizeh, remarkable for the depth and regularity of the grooves in it No.13, piece of limestone from Gizeh, showing how closely holes were placed together in removing material by drilling; the angle of junction shows that the groove of one hole just overlapped the groove of another, without probably touching the core of the adjacent hole thus the minimum of labour was required. The examples of tube drilling on a large scale are the great granite coffers, which were hollowed out by cutting rows of tube drill-holes just meeting, and then breaking out the cores and intermediate pieces; the traces of this work may be seen in the inside of the Great Pyramid coffer, where two drill-holes have been run too deeply into the sides; and on a fragment of a granite coffer with a similar error of work on it, which I picked up at Gizeh. At El Bersheh (lat. 27º 42') there is a still larger example, where a platform of limestone rock has been dressed down, by cutting it away with tube drills about 18 inches diameter; the circular grooves occasionally intersecting, prove that it was merely done to remove the rock.
132. The principle of rotating the tool was, for sma!ler objects, abandoned in favour of rotating the work; and the lathe appears to have been as familiar an instrument in the fourth dynasty, as it is in modern workshops. The diorite bowls and vases of the Old Kingdom are frequently met with, and show great technical skill. One piece found at Gizeh, No.14, shows that the method employed was true turning, and not any process of grinding, since the bowl has been knocked off of its centring, recentred imperfectly, and the old turning not quite turned out; thus there are two surfaces belonging to different centrings, and meeting in a cusp. Such an appearance could not be produced by any grinding or rubbing process which pressed on the surface. Another detail is shown by fragment No.15; here the curves of the bowl are spherical, and must have therefore been cut by a tool sweeping an arc from a fixed centre while the bowl rotated. This centre or hinging of the tool was in the axis of the lathe for the general surface of the bowl, right up to the edge of it; but as a lip was wanted, the centring of the tool was shifted, but with exactly the same radius of its arc; and a fresh cut made to leave a lip to the bowl. That this was certainly not a chance result of hand-work is shown, not only by the exact circularity of the curves, and their equality, but also by the cusp left where they meet. This has not been at all rounded off as would certainly be the case in hand-work, and it is a clear proof of the rigidly mechanical method of striking the curves.
[p. 177] Hand graving tools were also used for working on the irregular surfaces of statuary; as may be well seen on the diorite statue of Khafra found at Gizeh, and now at Bulak.
133. The great pressure needed to force the drills and saws so rapidly through the hard stones is very surprising; probably a load of at least a ton or two was placed on the 4 inch drills cutting in granite. On the granite core, No.7, the spiral of the cut sinks .1 inch in the circumference of 6 inches, or 1 in 60, a rate of ploughing out of the quartz and felspar which is astonishing. Yet these grooves cannot be due to the mere scratching produced in withdrawing the drill as has been suggested, since there would be about 1/10 inch thick of dust between the drill and the core at that part; thus there could be scarcely any pressure applied sideways, and the point of contact of the drill and granite could not travel around the granite however the drill might be turned about. Hence these rapid spiral grooves cannot be ascribed to anything but the descent of the drill into the granite under enormous pressure; unless, indeed, we suppose a separate rymering tool to have been employed alternately with the drill for enlarging the groove, for which there is no adequate evidence.
134. That no remains of these saws or tubular drills have yet been found is to be expected, since we have not yet found even waste specimens of work to a tenth of the amount that a single tool would produce; and the tools, instead of being thrown away like the waste, would be most carefully guarded. Again, even of common masons' chisels, there are probably not a dozen known; and yet they would be far commoner than jewelled tools, and also more likely to be lost, or to be buried with the workman. The great saws and drills of the Pyramid workers would be royal property, and it would, perhaps, cost a man his life if he lost one; while the bronze would be remelted, and the jewels reset, when the tools became worn, so that no worn out tools would be thrown away.
135. Of the various other details of mechanical work mention is made in different sections of this volume. The red marking of the mason's lines is described in section 63. The use of testing-planes in working surfaces, in section 170. The use of drafted diagonals, in section 55. The character of the fine joints, in section 26. The accuracy of levelling, in section 26. The fitting of the courses one on the other, in section 41. The arrangement of the courses on the ground before building, in section 168. The lugs left for lifting the stones, in sections 50, 55, and 63. The method of raising the stones, in section 169. The labour system employed on the Egyptian monuments in section 166. And the use of plaster, in section 128. A general statement of all these mechanical questions, with fuller details of some of the specimens and examples of work, will be found in a paper on the " Mechanical Methods of the Egyptians," in the Anthropological Journal for 1883.