The Technical Details of the Great Pyramid at Giza
Created | Updated Jan 28, 2002
The Great Pyramid at Giza, Egypt, stands almost exactly on the 30th parallel at latitude 29o 58’ 51’’ (29 degrees, 58 minutes of arc, fifty-one seconds of arc. One arc minute is a sixtieth of a degree, and one arc second is one sixtieth an arc minute.) If the Pyramid was intended to stand exactly on the thirtieth parallel, then this is an astonishing level of accuracy. But what if it had been intended to be slightly askew? There is a theory that if a man stood at the base of the Great Pyramid and wished to see the pole of the sky, then a slight correction would be necessary in order to counteract the effects of the curvature of the Earth’s surface. Rather than standing exactly on the thirtieth parallel, the pyramid would need to be sited at 29o 58’ 22’’. If this is true, then it means the true error of accuracy is just 29 arc seconds – 29 sixtieths of one sixtieth of one degree.
The four sides of the pyramid are aligned with the four cardinal points of the compass. On average, the deviation from true is just three arc minutes, or 0.015%. A difference of three degrees would go unnoticed by the naked eye, but the Egyptians went for greater accuracy in the alignment of the sides. The north – south axis of the pyramid is offset from true north by three sixtieths of a degree. By contrast, the Meridian Building at London’s Greenwich Observatory is offset by nine sixtieths.
The four sides measure, on average, just over 9063 inches. The north side is 755ft 4.9818 inches in length, the south side 756ft 0.9739 inches, the east 755 ft 10.4937 inches, and the west 755ft 9.1551 inches. The difference between the longest and shortest sides is slightly less than eight inches. The base of the pyramid therefore covers over thirteen acres.
The corners of the pyramid are not quite true right angles, but are also impressively close. On a normal modern building, the corners can be over a degree from true. It doesn’t affect the building structurally, and is not visibly obvious. On the Great Pyramid, the four corners are far, far closer. The north-eastern corner is 90o 3’ 2’’, the south-eastern corner is 89o 56’ 27’’, the south-western corner is 90o 0’ 33’’, whilst the north-western corner is an incredible 89o 59’ 58’’, just two arc seconds from being a true right angle.
In his book The Pyramids of Egypt, the Professor I.E.S Edwards (formerly keeper of Egyptian Antiquities at the British Museum) estimates that the pyramid consists of 2.3 million limestone and granite blocks. Of these, tens of thousands have been estimated to weigh over fifteen tons each, with the average sized blocks weighing around 2.5 tons – more than twice the weight of the average family car. Engineering logic and common sense dictates that the smaller blocks would be at the base of the pyramid, and after that the weight and size of the blocks would decrease, as the sheer logistics of getting blocks higher and higher increased. And to begin with the pyramid does follow this mode of thought. But, as the author Graham Hancock and his partner / photographer Santha Faiia discovered whilst trying – illegally, since the Egyptian Authorities imposed a ban on climbing the pyramid after tiring of clearing up the messy deaths of tourists – to climb the pyramid, this only holds true for so long, the first eighteen steps, or courses, to be exact. Course nineteen jumps to being in the fifteen ton range, from the 2.5 ton blocks below. By course nineteen you are already over 100 feet up. The Great Pyramid consists of 203 separate courses, with an average height from one course to the next being thirty inches. The 203rd course consists of several hundred blocks weighing around five tons each, and by this time the height is over 450 feet. Unfortunately, the very top few courses no longer exist, but a pole has been erected by means of scaffolding that reaches up to the estimated original height of 481.3949 feet.
It has been estimated that the Great Pyramid weighs about six million tons. Its original weight would have been greater, as the pyramid was once covered by 115,000 highly polished facing stones weighing approximately 10 tons each. Unfortunately, the majority of these had been shaken loose in a massive earthquake in AD1301, and were carted off by the natives for use in buildings in Cairo. Some still remained in place and were studied by William Flinders Petrie in the nineteenth century. He discovered that they were fitted together with tolerances of less than one hundredth of an inch – 0.020’’, to be precise - and were cemented in place so precisely that Petrie was unable to slip even the fine blade of his knife between the joints. He discovered that the tolerance for cutting a straight edge in the rock over a distance of 75 inches was just 0.01 of an inch from true.
The ratio between the original height (481.3949ft) and the perimeter (3023.16ft) turns out to be 2π – the same as the ratio between the radius and the circumference of a circle. Obviously then, if you multiply the height by 2π you get the perimeter, and if you divide the perimeter by two and then π you achieve the height. To achieve this ratio, it is necessary to build the slopes of the pyramid at 51 degrees, rather than the much easier to check 45 degrees.
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