The Great Pyramid of Khufu
Khufu Belongs to the Horizon
Original Height: 146.6 m (480.96 ft)
Current Height: 138.75 m (455.21 ft)
Length of Side: 230.37 (755.8 ft)
Angle: 51º 50’ 40
Estimated Volume: 2,521,000 cm
Khufu – 2575-2566 BC
The largest of the three pyramids at Giza, known as the Great Pyramid, is truly an astonishing work of engineering. It was built over a twenty year period. Some believe that it was built by slaves, but this is not true. One hundred thousand people worked on the great structure for three months of each year, during the Nile’s
annual flood when it was impossible to farm the land and most of the population was unemployed. The pharaoh provided good food and clothing for his workers, and was kindly remembered in folk tales for many centuries.
The sides are oriented to the four cardinal points of the compass and the length of each side at
the base It was constructed using around 2,300,000 limestone blocks, each weighing an average of 2.5 tons. Some blocks weigh as much as 16 tons. For centuries, the Great Pyramid was encased
in smooth limestone, but this was plundered in our era to build Cairo
It is believed the pyramid was built as a tomb for Fourth Dynasty Egyptian pharaoh Khufu (often Hellenicised as "Cheops") and was constructed over a 20-year period. Khufu's vizier, Hemon, or Hemiunu, is believed by some to be the architect of the Great Pyramid It is thought that, at construction, the Great Pyramid was originally 280 Egyptian cubits tall (146.5 metres (480.6 ft)), but with erosion and absence of its pyramidion, its present height is 138.8 metres (455.4 ft). Each base side was 440 cubits, 230.4 metres (755.9 ft) long. The mass of the pyramid is estimated at 5.9 million tonnes. The volume, including an internal
hillock, is roughly 2,500,000 cubic metres (88,000,000 cu ft). Based on these estimates, building the pyramid in 20 years would involve installing approximately 800 tonnes of stone every day. Additionally, since it consists of an estimated 2.3 million blocks, completing the building in 20 years would involve moving an average of more than 12 of the blocks into place each hour, day and night. The first precision measurements of the pyramid were made by Egyptologist Sir Flinders Petrie in 1880–82 and published as The Pyramids and Temples of Gizeh.[6] Almost all reports are based on his measurements. Many of the casing stones and inner chamber blocks of the Great Pyramid fit together with extremely high precision. Based on measurements taken on the north eastern casing stones, the mean opening of the joints is only 0.5 millimetres wide (1/50th of an inch)
Great Pyramid of Giza from a 19th-century stereopticon card photo
The pyramid remained the tallest man-made structure in the world for over 3,800 years unsurpassed until the 160-metre-tall (520 ft)
spire of Lincoln Cathedral was completed c. 1300. The accuracy of the pyramid's workmanship is such that the four sides of the base have an average error of only 58 millimetres in length.[9] The base is horizontal and flat to within ±15 mm (0.6 in).The sides of the square base are closely aligned to the four cardinal compass points (within four minutes of arc)based on true north, not magnetic north and the finished base was squared to a mean corner error of only 12 seconds of arcThe completed design dimensions, as suggested by Petrie's survey and subsequent studies, are estimated to have originally been 280 Royal cubits high by 440 Royal cubits long at each of the four sides of its base. The ratio of the perimeter to height of 1760/280 Royal cubits equates to 2π to an accuracy of better than 0.05% (corresponding to the well-known approximation
of π as 22/7). Some Egyptologists consider this to have been the result of deliberate design proportion. Verner wrote, "We can conclude that although the ancient Egyptians could not precisely define the value of π, in practice they used it Petrie, author of Pyramids and Temples of Gizeh concluded: "but these relations of areas and of circular ratio are so systematic that we should grant that they were in the builder's design Others have argued that the Ancient Egyptians had no concept of pi and would not have thought to encode it in their monuments. They believe that the observed pyramid slope may be based on a simple seked slope choice alone, with no regard to the overall size and proportions of the finished building
Materials
The Great Pyramid consists of an estimated 2.3 million blocks which most believe to have been transported from nearby quarries. The Tura limestone used for the casing was quarried across the
Casing stones
Casing stone in the British Museum
At completion, the Great Pyramid was surfaced by white "casing stones" – slant-faced, but flat-topped, blocks of highly polished white limestone. These were carefully cut to what is approximately a face slope with a seked of 5½ palms to give the required
do so with cement in the joints seems almost impossible". It has been suggested it was the mortar (Petrie's "cement") that made this seemingly impossible task possible, providing a level bed, which enabled the masons to set the stones exactly
Construction theories
Main article: Egyptian pyramid construction techniques
Clay seal bearing the name of Khufu from the great pyramid. On display at the Musée du Louvre.
Many alternative, often contradictory, theories have been proposed regarding the pyramid's construction techniques Many disagree on whether the blocks were dragged, lifted, or even rolled into place. The Greeks believed that slave labour was used, but modern discoveries made at nearby workers' camps associated with construction at Giza suggest that it was built instead by tens of thousands of skilled workers. Verner posited that the labour was organized into a hierarchy, consisting of two gangs of 100,000 men, divided into five zaa or phyle of 20,000 men each, which may have been further divided according to the skills of the workers
One mystery of the pyramid's construction is its planning. John Romer suggests that they used the same method that had been used for earlier and later constructions, laying out parts of the plan on the ground at a 1-to-1 scale. He writes that "such a working diagram would also serve to generate the architecture of the pyramid with precision unmatched by any other means" He also argues for a 14-year time span for its construction
A modern construction management study, in association with Mark Lehner and other Egyptologists, estimated that the total project required an average workforce of 14,567 people and a peak workforce of 40,000. Without the use of pulleys, wheels, or iron tools, they used critical path analysis to suggest that the Great Pyramid was completed from start to finish in approximately 10 years
Interior
Diagram of the interior structures of the Great Pyramid. The inner line indicates the pyramid's present profile; the outer line indicates the original profile.
The original entrance to the Great Pyramid is 17 metres (56 ft) vertically above ground level and 7.29 metres (23.9 ft) east of the center line of the pyramid. From this original entrance, there is a Descending Passage 0.96 metres (3.1 ft) high and 1.04 metres (3.4 ft) wide, which goes down at an angle of 26° 31'23" through the masonry of the pyramid and then into the bedrock beneath it. After 105.23 metres (345.2 ft), the passage becomes level and continues for an additional 8.84 metres (29.0 ft) to the lower Chamber, which appears not to have been finished. There is a continuation of the horizontal passage in the south wall of the lower chamber; there is also a pit dug in the floor of the chamber. Some Egyptologists suggest that this Lower Chamber was intended to be the original burial chamber, but Pharaoh Khufu later changed his mind and wanted it to be higher up in the pyramid
At 28.2 metres (93 ft) from the entrance is a square hole in the roof of the Descending Passage. Originally concealed with a slab of stone, this is the beginning of the Ascending Passage. The Ascending Passage is 39.3 metres (129 ft) long, as wide and high as the Descending Passage and slopes up at almost precisely the same angle. The lower end of the Ascending Passage is closed by three huge blocks of granite, each about 1.5 metres (4.9 ft) long. At the start of the Grand Gallery on the right-hand side there is a hole cut in the wall. This is the start of a vertical shaft which follows an irregular path through the masonry of the pyramid to join the Descending Passage. Also at the start of the Grand Gallery there is the Horizontal Passage leading to the "Queen's Chamber". The passage is 1.1m (3'8") high for most of its length, but near the chamber there is a step in the floor, after which the passage is 1.73 metres (5.7 ft) high.
Queen's Chamber
Richard Pocockes sketch of Pyramid of Cheops from 1754.
The Queen's Chamber is exactly half-way between the north and south faces of the pyramid and measures 5.75 metres (18.9 ft) north to south, 5.23 metres (17.2 ft) east to west, and has a pointed roof with an apex 6.23 metres (20.4 ft) above the floor. At the eastern end of the chamber there is a niche 4.67 metres (15.3 ft) high. The original depth of the niche was 1.04 metres (3.4 ft), but has since been deepened by treasure hunters.[citation needed]
In the north and south walls of the Queen's Chamber there are shafts, which unlike those in the King's Chamber that immediately slope upwards, are horizontal for around 2 m (6.6 ft) before sloping upwards. The horizontal distance was cut in 1872 by a British engineer, Waynman Dixon, who believed a similar shaft to the King's Chamber must also exist. He was proved right, but because the shafts are not connected to the outer faces of the pyramid or the Queen's Chamber, their purpose is unknown. At the end of one of his shafts, Dixon discovered a ball of black diorite (a type of rock) and a bronze implement of unknown purpose. Both objects are currently in the British Museum.
The shafts in the Queen's Chamber were explored in 1993 by the German engineer Rudolf Gantenbrink using a crawler robot he designed, Upuaut 2. After a climb of 65 m (213 ft),the discovered that one of the shafts was blocked by limestone "doors" with two eroded copper "handles". Some years later the National Geographic Society created a similar robot which drilled a small hole in the southern door, only to find another door behind it. The northern passage, which was difficult to navigate because of twists and turns, was also found to be blocked by a door
Research continued in 2011 with the Djedi Project. Realizing the problem was that the National Geographic Society's camera was only able to see straight ahead of it, they instead used a fiber-optic "micro snake camera" that could see around corners. With this they were able to penetrate the first door of the southern shaft through the hole drilled in 2002, and view all the sides of the small chamber behind it. They discovered hieroglyphs written in red paint. They were also able to scrutinize the inside of the two copper "handles" embedded in the door, and they now believe them to be for decorative purposes. They also found the reverse side of the "door" to be finished and polished, which suggests that it was not put there just to block the shaft from debris, but rather for a more specific reason
Grand Gallery
The Grand Gallery of the Great Pyramid of Giza
The Grand Gallery continues the slope of the Ascending Passage, but is 8.6 metres (28 ft) high and 46.68 metres (153.1 ft) long. At the base it is 2.06 metres (6.8 ft) wide, but after 2.29 metres (7.5 ft) the blocks of stone in the walls are corbelled inwards by 7.6 centimetres (3.0 in) on each side. There are seven of these steps, so, at the top, the Grand Gallery is only 1.04 metres (3.4 ft) wide. It is roofed by slabs of stone laid at a slightly steeper angle than the floor of the gallery, so that each stone fits into a slot cut in the top of the gallery like the teeth of a ratchet. The purpose was to have each block supported by the wall of the Gallery rather than resting on the block beneath it, which would have resulted in an unacceptable cumulative pressure at the lower end of the Gallery
At the upper end of the Gallery on the right-hand side there is a hole near the roof that opens into a short tunnel by which access can be gained to the lowest of the Relieving Chambers. The other Relieving Chambers were discovered in 1837/8 by Colonel Howard Vyse and J. S. Perring, who dug tunnels upwards using blasting powder.
The floor of the Grand Gallery consists of a shelf or step on either side, 51 centimetres (20 in) wide, leaving a lower ramp 1.04 metres (3.4 ft) wide between them. In the shelves there are 54 slots, 27 on each side matched by vertical and horizontal slots in the walls of the Gallery. These form a cross shape that rises out of the slot in the shelf. The purpose of these slots is not known, but the central gutter in the floor of the Gallery, which is the same width as the Ascending Passage, has led to speculation that the blocking stones were stored in the Grand Gallery and the slots held wooden beams to restrain them from sliding down the passage This, in turn, has led to the proposal that originally many more than 3 blocking stones were intended, to completely fill the Ascending Passage.[citation needed]
At the top of the Grand Gallery, there is a step giving onto a horizontal passage some meters long and approximately 1.02 metres (3.3 ft) in height and width, in which can be detected four slots, three of which were probably intended to hold granite portcullises. Fragments of granite found by Petrie in the Descending Passage may have come from these now-vanished doors.
King's Chamber
Sarcophagus in the King's chamber
The King's Chamber is 10.47 metres (34.4 ft) from east to west and 5.234 metres (17.17 ft) north to south. It has a flat roof 5.974 metres (19.60 ft) above the floor. 0.91 m (3.0 ft) above the floor there are two narrow shafts in the north and south walls (one is now filled by an extractor fan in an attempt to circulate air inside the pyramid). The purpose of these shafts is not clear: they appear to be aligned toward stars or areas of the northern and southern skies, yet one of them follows a dog-leg course through the masonry, indicating no intention to directly sight stars through them. They were long believed by Egyptologists to be "air shafts" for ventilation, but this idea has now been widely abandoned in favour of the shafts serving a ritualistic purpose associated with the ascension of the king’s spirit to the heavens
The King's Chamber is entirely faced with granite. Above the roof, which is formed of nine slabs of stone weighing in total about 400 tons, are five compartments known as Relieving Chambers. The first four, like the King's Chamber, have flat roofs formed by the floor of the chamber above, but the final chamber has a pointed roof. Vyse suspected the presence of upper chambers when he found that he could push a long reed through a crack in the ceiling of the first chamber. From lower to upper, the chambers are known as "Davison's Chamber", "Wellington's Chamber", "Nelson's Chamber", "Lady Arbuthnot's Chamber", and "Campbell's Chamber". It is believed that the compartments were intended to safeguard the King's Chamber from the possibility of a roof collapsing under the weight of stone above the Chamber. As the chambers were not intended to be seen, they were not finished in any way and a few of the stones still retain masons' marks painted on them. One of the stones in Campbell's Chamber bears a mark, apparently the name of a work gang
The entrance of the Pyramid
The only object in the King's Chamber is a rectangular granite sarcophagus, one corner of which is broken. The sarcophagus is slightly larger than the Ascending Passage, which indicates that it must have been placed in the Chamber before the roof was put in place. Unlike the fine masonry of the walls of the Chamber, the sarcophagus is roughly finished, with saw marks visible in several places. This is in contrast with the finely finished and decorated sarcophagi found in other pyramids of the same period. Petrie suggested that such a sarcophagus was intended but was lost in the river on the way north from Aswan and a hurriedly made replacement was used instead.
Modern entrance
Today tourists enter the Great Pyramid via the Robbers' Tunnel, a tunnel created around AD 820 by Caliph al-Ma'mun's workmen using a battering ram.[36] The tunnel is cut straight through the masonry of the pyramid for approximately 27 metres (89 ft), then turns sharply left to encounter the blocking stones in the Ascending Passage. It is believed that their efforts dislodged the stone fitted in the ceiling of the Descending Passage to hide the entrance to the Ascending Passage and it was the noise of that stone falling and then sliding down the Descending Passage, which alerted them to the need to turn left. Unable to remove these stones, however, the workmen tunnelled up beside them through the softer limestone of the Pyramid until they reached the Ascending Passage. It is possible to enter the Descending Passage from this point, but access is usually forbidden
