Читать книгу The Aswân Obelisk - Reginald Engelbach - Страница 4

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(3) The obelisk is 41.75 metres long, lying with its point 18.5 degrees north of east, and sloping down towards the butt at an angle of 11 degrees, making the base of the pyramidion 7.05 metres above the level of the butt. When complete, the obelisk would have weighed 1168 tons English.

It is curious that, during all the years that this obelisk has been known, those who were interested in the ancient methods of quarrying have not taken the trouble to clear it. Nearly every work in which it is mentioned dismisses it in a few sentences. Both Gorringe in his Egyptian Obelisks and Bædeker give its length as 95 feet and the width at the butt as 11 feet 1.5 inches. How they arrived at the latter figure passes my understanding, as it was buried under a chip-heap to a depth of 7 metres. Perhaps the measurements were given by the original writer, whoever he may have been, not as a fact, but as a prophecy.

The measurements of the obelisk are:

Total length	41.75	metres.
Base	4.20	metres.
Base of pyramidion	2.50	metres.
Height of pyramidion	4.50	metres.
Weight when finished	1168	English tons.

Round the obelisk, partly separating it from the surrounding rock, is a narrow trench, whose depth averages about 2/3 that required to disengage it to a square section.

Plate is a plan, with sections, of the obelisk to a scale of 1/100, and plate II, nos. 1 and 2, shews the obelisk viewed from the tip and butt respectively; the trench around the obelisk can be seen in plate II and in plate III, no. 1, and is discussed in chapter ii.

As to the date of this obelisk, I have found nothing which gives any real clue to it. One utiy, in the reign of atshepsôwet, mentions an obelisk of 108 cubits (56.7 metres) long, which is longer than that of Aswân, even if we allow for the pedestal as having been included in the measurement (see BREASTED, Ancient Records, II, p. 156, and section 43 of this volume). Neither can the Aswân obelisk be an abortive attempt to extract the obelisk, a part of which is now at Constantinople, as the thickness of what is now the base is only 2.37 metres, whereas the Aswân obelisk measures 2.50 metres at the base of the pyramidion. Unfortunately we are compelled to leave the question of the date open, until we get some definite evidence, which may well appear when the whole quarry is completely cleared. {4}

(4) There are abundant traces that the rock, from which the obelisk was to be extracted, was reduced to an approximately correct level by burning and wedging, the former being used wherever possible. In the excavations, a large quantity of burnt and semi-burnt mud bricks were noticed, while a considerable percentage of the chips round the obelisk and other quarries had the pinkish-brown colour and crumbling texture peculiar to burnt granite. Some large pieces of rock shew quite clearly how the burning was done; it appears that a stack of dried reeds was banked with brick, near a fissure if possible, and after firing, the rock was easily hammered away. It is very likely that water was poured on the hot stone to make it break up. This method of heating and chilling is used on the granite in India at the present day. Traces of burning are seen in the obelisk area at A and B on plate V, no. 1. Such a vast amount of stone has been removed in the neighbourhood which shews neither wedge nor chisel marks that, without the proof of the burnt brick and stone, we should have been driven to the conclusion that burning was the method employed [1].

Fig. 1.—Typical wedge-slots.

Wedge-marks may be seen on plate III, no. 3, on the left of the picture [2]. Typical examples are shewn on plate III, no. 2, and in figure 1. In nearly every case I observed, a small trench had been cut out by chisels along the proposed line of fracture, presumably to get below the surface, which is often decomposed by exposure, and which would crumble instead of tearing the stone apart. As to whether these wedges were of wood, and made to expand by wetting, I am not certain, but I believe that they were not, the reason being that the slots always taper inwards, and it appears to me that a wetted wedge would tend to spring out rather than exert a lateral force on the stone. In the only case where I have seen wetted wedges used (experimentally on limestone), the wedge-slots were cut with parallel walls.

[1] In some cases a ferruginous (?) stratum in the granite has decomposed the rock with an appearance of its having been burnt. Long exposure of the rock also rots it to a considerable depth, but in the majority of cases where the rock has been removed without wedges or chisels, neither of the above causes can have anything to do with it.

[2] An examination of the wedging-off of blocks in the quarries about Aswân shews that often the wedges have acted perfectly, but the block has not been removed. A crowbar acting in each slot would be ample to remove most of these. Can it be that the crowbar or jemmy of metal was not known?

Assuming, then, that hammered metal wedges were used and not wooden wedges made to expand by the action of water, it remains to be seen whether the plug-and-feather method, such as is used to-day, was employed, or whether the metal wedges engaged with the stone without the thin sheets of metal on either side which we now call ‘feathers’. The advantages of the plug-and-feather method are that it reduces the width of the slot at the top, leaving it wider below and hence to a large extent preventing the sharp edge of the wedge from touching the bottom of the wedge-slot, and that, since the faces of the feathers are smooth, it tends to {5} obtain the maximum advantage of the lateral force exerted by the wedge in the most evenly distributed way and with a minimum of friction. Now nearly all the ancient wedge-slots appear perfectly smooth inside—just as if they had been polished. This would be a disadvantage in using feathers, as there would be a greater tendency for them to jump out at the first blow. Nothing seems to be gained by polishing. Personally I favour the assumption that the Egyptians used the plug-and-feather, but the question is best left open for the present for lack of conclusive evidence. Photographs of two iron wedges from the Ramesseum are given in PETRIE, Tools and Weapons, plate XIII, B 16, 17. They appear to date to about 800 B. C. Feathers, of unknown date, but probably late, are given in the same volume on plate XIII, B 22, 23. It is a bare possibility that the smoothness of the sides of the wedge-slots is due to the fact that the slots were made without chisels, such as by scraping the granite with emery-stone, or that after they had been roughed-out by chisels they were finished by this means.

Sometimes, along a crack, enormous wedges were used, the largest I noticed being 0 m. 25 cent. long, spaced one metre apart. In any case the largeness of the wedges leads us to suppose that the Egyptians must have had large hammers. I do not think that the sledge-hammer, such as we use to-day, was known to the Egyptians, though mallets were common. I believe it likely that heavy rammers, used vertically by more than one man, must have been used to make these wedges act. Mr. C. Firth has pointed out to me a black granite hammer found at Saqqârah, now in the Cairo Museum. Though this example is of the Old Kingdom, it seems quite likely that a similar hammer was used for driving in the wedges. A photograph of the hammer is shewn in plate IV, no. 2. To-day the quarrymen use very small fat steel punches in conjunction with a sledge-hammer. Some large wedge-marks are seen in plate III, no. 2, at the top of the picture.

(5) It seems that the intention of the Egyptians was to leave the north wall of the north trench at a level slightly above that of the obelisk. The exceptions to this are the wedged-out block seen on plates and II, no. 2 at A, and the (now) entrance to the bottom of the north trench at B. I believe these blocks to have been removed at a date later than that of the obelisk; the block A has been wedged out by a long channel instead of separate slots, while at B it is obvious that stone has been removed for building, since the inner face has been chisel-dressed. Near here, too, I found a block containing a ‘jumped’ hole blackened by gunpowder. Had the ancients wished to remove the trench wall at B, there is a crack running along it parallel to the ground, which would make its removal an easy matter by burning from the outside [3]. It seems, therefore, that the north wall of the north trench was intentionally left; the probable reasons are discussed in section 23. It will be noticed, in plate II, that the top of this wall has been roughly hammer-dressed near the butt, and to a certain extent near the pyramidion. How far it was intended to reduce the south wall of the south trench is not certain; it depends on the method to be used in getting the obelisk out of the quarry, and is dealt with in sections 21–23. There are indications that it was to be reduced to a considerable extent. {6}

[3] There is not a trace of burning within 6 feet of the obelisk.

(6) At intervals in the trench around the obelisk there are traces of squarish holes, generally going down to about the level at which the bottom of the obelisk was to be. These are seen more clearly in the south trench than in the north, and can in some cases be traced up the side of the obelisk itself. Besides these there are the deep holes seen at C and D on plate . I believe that the holes C and D were made at the very commencement of the work to study the quality of the granite. The holes along the trench seem to have been made with the same purpose, and as a means of setting out the perimeter of the obelisk. There are indications that they were made when the removal of the top layers of rock were still in progress.

(7) From the beginning of the work on this obelisk, cracks and fissures seem to have given a great deal of trouble and anxiety. Though parting fairly evenly under the action of wedges, the natural fissures of granite are most erratic; a small crack at one level or position may, in a couple of metres, become a fissure into which one can insert the blade of a knife, and conversely, a fissure traceable for 5 metres will suddenly disappear. Hence every fissure or crack, as it appeared, had to be rigorously examined, to see its probable effect on the obelisk when completed. The examination seems to have been made in three ways, which I believe to have been of two dates. The original workers method was to hammer out a depression by means of a spherical ball of about 12 lbs. weight, of a very tough greenish-black stone (section 13), until the fissure either disappeared or became larger. These examination hammerings can be seen in plate at j, k, n, and p, n being also seen in the photos on plate II no. 2 and plate III no. 1. In the depression, sometimes at one place and sometimes at two, a small fillet was left at the level of the face of the obelisk, and apparently polished; the object seems to have been to compare the state at the surface with that at the bottom of the depression. The second method was to chisel out a narrow channel right along the crack and to polish it. In some cases, as at the end of fissure i on plate , the three red lines, drawn to guide the stone-cutter, can be clearly seen at the end of the channel. It seems likely that the channel method was that used by the later workers who examined the obelisk as to the possibility of extracting a smaller one from it, as the channels are only found in the parts within the area of the smaller obelisk (section 10). I think that the channels were cut over discolourations and superficial flaws, recognised as such and left by the original workmen. The statement made by Barber, in his The Mechanical Triumphs of the Ancient Egyptians, that the grooves are made at some later date with the intention of cutting up the obelisk, is impossible, as two (h and i, plate ) run transversely across the obelisk, where all the wedging and cutting in the world would not part the stone. The line of small punch-holes at H, however, was undoubtedly made in modern or mediæval times to extract a block from the side of the obelisk, and it is a marvel that the obelisk has not been used as a quarry throughout the ages. The third method was to cut with a chisel oblong holes, tapering sharply inwards, on the crack to be examined. It is possible that this was the work of the original party, done in haste on the occasion of an inspection. This method is seen at the base of the pyramidion on plate .

The most serious flaws in the obelisk are those lettered a, b, c, d, k, m, o and p; any one of these would give one seriously to think as to the advisability of abandoning the work forthwith. {7} Fissure a meets fissure b and settles, once and for all, that the pyramidion must be set back at least half a metre. Fissure c is even more radical. Fissures d, e and f all seem to have connection with one another and make a considerable reduction in width necessary; those between k and m carry a similar warning on the south side, while m and o necessitate shortening the obelisk from the butt end. The last fissure completely separates the corner of the obelisk from the rest.

It might well be asked: Why was the work continued so long after such bad fissures had been discovered? The answer may be that none of these fissures appeared to be serious, even a short distance above the present level of the face of the obelisk. The north and south trenches do not give evidence that the granite was in a bad state, except at ab, l, o and p.

It is likely that the black line π, drawn across the base of the obelisk to shorten it by over 2 metres, was made by the original workers; this is indicated by the fact that, below this line, the hammer-dressing has been left in a rougher state than that on the remainder of the face of the obelisk; further, the trench, which was intended to separate the base of the obelisk, was abandoned earlier than those on the north and south sides, probably as soon as the fissures shewed themselves to be deep.

There is a curious fissure in the hole F on plate which runs downwards and slightly inwards to the obelisk. Like fissures k to m, it would of itself necessitate a reduction in the original width. It appears, at first sight, that this is the beginning of undercutting the obelisk, but it is not at the level at which this would be commenced.

(8) It would not be out of place, perhaps, to speculate for a moment on the method of obtaining a flat surface along the upper face of the obelisk. I think the method used was by means of boning rods—the method used to-day. For the benefit of those not acquainted with their use, a brief description will suffice. Boning rods are a set of equal, usually T-shaped pieces of wood. One is held upright at each end of the surface which it required to straighten. A man standing at either end, if he sight along the top of these boning rods, can see if a third boning rod, placed anywhere between them, is above or below the line joining them. Thus the surface can be tested anywhere along the obelisk until it is made to slope evenly down along its whole length.

Boning rods for dressing moderately large blocks of stone are shewn in PETRIE, Tools and Weapons, plate XLIX, B 44–46. These measure only about 3 inches high and their tops were connected by a cord. In the case of an obelisk, the cord would be useless owing to the sag, so it seems probable that the sighting method described above was that employed by the ancient Egyptians.

In the setting out of the obelisk, no allowance is made for the slight convexity or entasis, in a longitudinal and transverse sense, which is to be observed in most of the known obelisks. If there was to be a convexity, it was made at a later stage [4]. {8}

[4] It will be noticed in plate , nos. 2 and 3, that the slight convexity across the obelisk seen in some places, does not extend the whole length, neither is it even as regards either edge.

(9) When the face of the obelisk had been made fairly flat by hammer-dressing, lines were scratched on it with a chisel, and filled in with black paint. The remains of the lines for the original scheme are clearly traceable. These are shewn on plate , α and β. How much reduction was allowed for as regards the final dressing and polishing, we do not know; it was probably only the matter of a couple of centimetres. At the west end of the south trench the reduction of the side of the obelisk to the guide line has been begun. This can be seen at J to K on plate . It now forms a kind of bevel and, as far as it extends, obliterates the vertical markings on the wall of the trench. On the east end of the north trench the trench itself has been moved inwards, from G to H, to be nearer the guide-line. The reason may either be that the workers found themselves too far from the guide-line, or that the guide-line was changed during the progress of the work, perhaps through fear of a fissure.

Before the original workers abandoned their work they seem to have made several attempts to set out a slightly reduced obelisk, which would avoid all serious cracks by reducing the length and thickness of the original design. This is seen in the lines γ δ ε ζ and the transverse lines ι κ λ μ. The last four lines are so faint that they can only be seen just after sunrise or before sunset, and it is not clear with which of the longitudinal lines they connect. On the south side the lines are quite clear, but on the north side there seem to have been more lines even than those shewn on plate . These lines γ δ ε ζ, do not lie at equal distances from either of the two centre lines η and θ.

There is no doubt in my mind that the original obelisk was to have had a straight-edged pyramidion, as the rough edge of the boundary trench lies evenly on either side of the centre line η.

(10) The outline for another, and most probably later, obelisk is set out on a new centre line θ, and keeps closely to the north edge of the original design, avoiding the series of fissures on the south. Just before sunset, the tentative outlines for the curved pyramidion can be traced; plate III, no. 3, taken at that time, shews these lines. In this, the right-hand curve appears to engage with a line to the north of that engaged by the curve next to it; this is only an effect of light and they really engage as shewn on plate .

I have outlined the original design and the later scheme, in red. Though the lines setting out these obelisks are easily traceable, the colouring is mine, and is only intended to shew up the lines more clearly. Since there are some actual red lines on the obelisk, another colour would have been preferable; considerations of cost in printing have limited the plate to two colours. In outlining the later design in red, I have chosen the larger pyramidion, as the shape decided on. There is no proof of this, but the proportions are, to me, more effective, and there is no reason for abandoning the odd metre of difference, as the stone here is perfectly sound.

Taking the longer pyramidion, we have the following dimensions for the obelisk:

	metres.
Total length	32.10
Pyramidion height	5.31
Pyramidion base	2.02
Obelisk base	3.15

{9}

(11) I had intended to give a diagram of the better-known obelisks superimposed. I found it, however, almost impossible to get the sides of the obelisks distinct one from another without making the scale inconveniently large. I give, therefore, a table shewing the principal dimensions of ten examples. Those marked with an asterisk are scaled off photographs, making slight allowances for foreshortening.

OBELISK.	BASE (METRES).	PYRA- MIDION BASE.	PYRA- MIDION HEIGHT.	TOTAL HEIGHT.	TAPER 1 IN	WEIGHT (IN TONS ENGLISH)
Aswân	4.20	2.50	4.50	41.75	24.3	1168
Aswân (later project)	3.15	2.02	5.31	32.10	23.7	507
Lateran	2.87	1.90*	4.50*	32.15	30.7	455 [5]
atshepsôwet	2.40	1.78	2.96	29.50	42.8	323
Vatican	2.69	1.80	1.34	25.31	26.9	331
Paris	2.42	1.54	1.94	22.84	23.7	227
London and New York	2.37	1.63*	1.65*	21.18	30.5	193 [6]
Maarieh	1.90	1.23*	2.00*	20.42	27.5	121 [5]
Tuthmôsis Ist	2.15	1.40*	2.39*	19.60	24.2	143

[5] After Gorringe.

[6] Average, after Gorringe.

It will be seen how close the measurements of the Aswân modified scheme are to those of the Lateran obelisk. Except for the height and base, I have had to scale the latter off a photograph, so the resemblance may be even closer.

It is also perhaps more than a coincidence that the base of the later project is the same as that of the obelisk fragment before Pylon VII at Karnak, namely 3.15 metres. Legrain, writing in the Annales du Service, vol. V, pp. 11 and 12, remarks, about this Pylon VII obelisk: “L’obélisque d’Hatshopsitou mesure 29 m. 50 cent. de hauteur et 2 m. 40 cent. à la base. Si nous admettons des proportions semblables pour deux monuments contemporains, la base de l’obélisque de Thoutmôsis III au VII^e pylône étant 3 m. 15 cent.–3 m. 10 cent., nous arrivons au chiffre approximatif de 37 m. 77 cent. comme hauteur de l’obélisque de Thoutmôsis III dont nous avons retrouvé les fragments cette année devant la face sud du VII^e pylône. (Footnote): J’ai pris comme base de ce calcul hypothétique (29.50 ×3.15)/2.46 en comptant sur la plus grande largeur de la base, qui, dans l’antiquité, se voyait le mieux.” This year, a fragment of the companion (or perhaps the same) obelisk has been found, which just reaches up to the wording of the Horus name of the king—that is to within a couple of metres of the base of the pyramidion. Although only one edge remains, I found that, by measuring from the centre of the vertical lines flanking the inscription, that the distance to the edge was 1.04 metre, making the width here 2.08 metres, which is almost exactly that of the outline on the Aswân obelisk. Legrain, in estimating the height of the obelisk before Pylon VII, assumes that the taper was the same as that of the obelisks of atshepsôwet, but, from the table above, it will be seen that the taper of her obelisks is exceptionally small, so his estimate is likely to err on the large side. The outline on the Aswân {10} obelisk may therefore be either for what is now the Lateran obelisk, or those of Pylon VII; there is no evidence to shew for which it was intended.

It is likely that the later scheme was, in its turn, abandoned from fear that the granite was not sound, especially near fissure p. In any case, the reduction of the large obelisk to obtain a smaller one would be a piece of work almost comparable to starting the work over again on a new site, where the rock was likely to be of better quality.