air shafts

The Purpose of the Shafts in Khufu's Akhet

Ventilation ducts or chimneys for incense smoke

c.1196 AD, Islamic scholar, Abd al Latif, noticed the casing of the two main pyramids at Giza was still intact. Some of Abd al Latif's companions made their way up to a chamber in the upper part of the pyramid: "in the upper part were openings apparently designed to let in air and light."

Although it's not known if the upper shafts were originally open to the sarcophagus chamber, this mention of the upper shafts, indicates that at least 800 years ago, the lower ends of the shafts were open.

The sarcophagus chamber was discovered c.820 AD, so for at least ~400 years before Abd al Latif visited the chamber, treasure hunters, and tomb robbers had access to it. If the lower ends of the shafts were originally closed, they may have detected anomalies in the walls and cut through to the shafts.

John Greaves, an English mathematician and astronomer, travelled to Egypt in 1646, where he "...hoped to find in the Great Pyramid a datum that might help to establish the dimensions of the planet." In the upper or sarcophagus chamber, he noted: "two inlets or spaces, in the south and north sides of the chamber, just opposite from one another" (Greaves 1646: 73)

After publication of Greaves research, in a booklet entitled 'Pyramidographia', Dr. William Harvey, discoverer of the circulation of blood, was "surprised that Greaves had not described, or apparently even discovered, any conduits by means of which the central chambers in the Pyramid could be ventilated from the exterior." (Tompkins 1971: 29)

The two inlets in the north and south sides of the sarcophagus chamber that Greaves had noted have outlets in the exterior face of the core masonry. These outlets were uncovered by Vyse and Perring, who surveyed the pyramid from 1837-38. After clearing them of sand, stones and debris, the shafts functioned as ventilation ducts. Badawy suggested the origin of the term 'air channels' probably dates from this time. (from Badawy, MIOAVB 1964: 189, note 4: J.S. Perring, The Pyramids of Gizeh, Part I: The Great Pyramid)

Similar shafts to those found in Khufu’s pyramid are found in the late Dynasty 5 Chapel of Ptahhotep at Saqqara:

“The east and south walls are pierced just below the ceiling by a shallow longitudinal opening, both wall and roof being cut away to form the shaft, which slants down into the chamber, presumably from the open air above. As the openings are at present blocked up and deeply buried, their further direction towards the outside of the mastaba could not be investigated. They were evidently designed to admit light or air, perhaps both. I do not know whether such apertures frequently occur in mastabas. Something similar exists in the pillared hall also, and I have observed the like in the hall of a mastaba in the necropolis of Giza. The manner of this construction can be seen in Pl. ii.” (The Mastaba of Ptahhetep and Akhethetep at Saqqareh, Part I - The Chapel of Ptahhetep and the Hieroglyphs, Davis 1900: 5)

Ptahhotep, the owner of the mastaba chapel, was a man “Worthy before the great god Osiris and Anubis chief of the western dead” (Quibell 1898: 33-4)

An inscription from the southern false door in the west wall, outer right jamb: “Crossing the heaven so perfectly in peace, proceeding to the mountain of the necropolis, so that he may be taken possession of by the ancestors and by his kas, the foremost one, possessor of the state of imakhu, and so that invocation offerings might be made for him at the offering place in his house of eternity. For he has grown old most perfectly in the sight of Osiris, the first under the king, Ptahhotep.” (Strudwick 2005: 213)

The names of some of the many funerary domains mentioned in his mastaba: ‘The Estate of Khufu’; ‘The Nekhen Sanctuary of Osiris’; The inet foundation of Snefru’; ‘Snefru is firm’.

The chapel is 5.31 x 2.18 m (about half the size of Khufu’s sarcophagus chamber), and is 3.76 m high. It has two false doors, an offering slab, and two wide shafts - one has the opening at the top of the south wall, and the other opening at the top of the east wall:

plan of the chapel

West wall

detail of shaft opening in the south wall

(assuming the measurements are 5 1/4” and 4 1/2”, the calculated angle of incline of the shaft is 40.6 degs - the angle as shown in the drawing is ~43 degs)

The height of the shaft shown in the detail is ~10 cm (about half the height of the shafts in Khufu’s pyramid). The shafts have wide inlets into the ‘chapel.' The opening in the south wall is ~1.1 m wide and centred in the wall at the junction of wall and ceiling - its floor, ~11.5 cm below ceiling level. The opening in the east wall is ~1,25 m wide.

South wall

East wall

The shafts probably had outlets in the roof of the mastaba, which meant the false doors and offering slab were faintly illuminated by daylight. The smoke of incense used in the offering rituals could also be vented out through the shafts, and perhaps also provided a means for the 'spirit' of the deceased to ascend to the sky.

The Pyramid Texts mention the deceased ascending to the sky on the smoke of incense:

"the mother of Pepi Neferkare, Nut, the (grand)father of Pepi Neferkare, Shu, and the (grand)mother of Pepi Neferkare, Tefnut, will take Pepi Neferkare to the sky, to the sky on the smoke of incense.....” N 514

Part of a recitation repeated four times with incense on the fire: “Someone / Horus / Seth / Thoth / the god / Osiris / Eyes-Forward / you have gone with his ka. W 20.

“The fire has been set, the fire has arisen. The incense has been set, the incense has arisen......Unis’s father Atum will take the arm of Unis and allot Unis to those gods who are wise and experienced the Imperishable Stars.” W 176

“East / South walls have upward sloping ceiling level holes linking to the Mastaba roof – their position would illuminate the false-doors. There may have been a religious purpose, such as a route for the Ba to access the terrestrial world.” ( link )

Khafre's 'Lower Temple' also has slits along the top edge of the north and south walls of the western part of the 'Great Hall' that provided ventilation:

"The ventilators are a peculiar feature of the building, though somewhat like those to be seen in the tombs. They were formed by sloping slits along the top edge of the walls, a few inches wide, and usually 41 inches long. Only one remains perfect, that opening out of the chamber of loculi; this slit opens into a rectangular shaft, which rises to some way above the roof, and there opens with a square mouth of alabaster on the face of the upper court wall. The mouth is on the same side of the shaft as the slit, and hence the only light entering is reflected from the side of the shaft. The slits cut for these ventilators exist all along the Western part of the great hall, and are marked on the walls in the plan.” (Petrie 1883: 131)

Petrie 1883: Pl. vi

Before the shafts in Khufu’s sarcophagus chamber were fitted with modern ventilation equipment, Lepre measured the temperature during autumn, winter and spring, and found it fluctuated between 21 ..... 26.7 C degs. (Lepre 1990: 97)

The ~55 m2 chamber can accommodate 50+ people - if the funerary cortege had accompanied the bodily remains of the king all the way up to the sarcophagus, the shafts supplied fresh air and helped regulate the temperature. After the final ceremonies, the shafts may have been sealed to prevent bats, insects, fine wind-borne sand and water from violating the sanctity of the chamber.

The middle (‘Queen’s’) chamber, may have had a secondary function as part of a contingency plan in case the king died before the upper chamber was completed, or if structural failure of the ceiling occurred during the construction of the upper chamber.

According to Vyse, Edgar and Lepre, once the shafts had been cleared of debris, they effectively ventilated the chamber:

Vyse believed the upper shafts were made for ventilation after he noted that once the southern ‘air-channel’ had been cleared of debris, “an immediate rush of air took place, and we had the satisfaction of finding that the ventilation of the King’s Chamber was perfectly restored and that the air within it was cool and fresh.......... Had not the upper part of the latter channel been forced, and that of the southern filled up with the above-mentioned stone, both of them would in all probability have remained open, and the ventilation of this wonderful structure would have continued as perfect as when it was first built.........The great importance of the King’s Chamber is also proved by the air-channels expressly made for its ventilation,.......” He also noted that “As these channels were subsequently found to have been for the ventilation of the King’s Chamber, they are called Air Channels.” (Vyse Vol. 1, 1860: 3 (note 2), 286-8)

“There is always a more or less strong current of air blowing through the south channel, up or down according as the wind blows from the north or south. It is sometimes strong enough to blow out the light of a candle when it is held inside the channel’s inner mouth.” (Edgar 1910: 183)

“There is one distinction between the Great Pyramid and all other pyramids to which I desire to call attention, although it is well known to you. The Great Pyramid of Gizeh is provided with ‘air-channels," and this, incidentally, is proof that this monument at all events was not intended for a tomb. The dead do not breathe! When I was at the Pyramid in 1928 I got permission from the Egyptian government to clear the debris from these channels. During my first visit in 1909, the South Air-Channel of the King’s Chamber was quite open and a good breeze constantly passed through it, but the North Air-Channel of this chamber was entirely stopped up with stones and hardened dust. My object during this last visit was to clear out this obstruction from the North Channel. The South Channel had also during the past twenty years become blocked with debris.

However, I found it a comparatively easy matter to remove the debris from the South Channel, but work on the North Channel was much more difficult. I employed several Arab workers to push down a long boring rod from the outside of the Pyramid on the north side. At the end of this rod was a scoop of metal by which they were able to extract the debris a little at a time. As the North Air-Channel is over 200 feet in length, and only 9 inches square in bore, it was an arduous task to remove all the hardened debris. My men worked on it for six weeks continuously. I am glad to say that their labors were entirely successful, every particle of debris being removed; and now, seeing that both South and North Air-Channels of the King’s Chamber are quite open, there is a constant cool air-current passing through the Pyramid.

In order to prevent these channels again becoming stopped up with debris, I directed my men to construct certain masonry work at their outer ends. This masonry is arranged in such a way that it will be impossible for dust or stones to again be washed into the channels by rain.” (‘The Great Pyramid - Why was it built? Who built it?’ 1928 address by Morton Edgar link )

“The southern air shaft, being 175’ long, rises at a 45-degree angle; while the northern shaft, being 235’ in length, ascends at an angle of 31 degrees. Both succeed in admitting a flow of fresh air into the chamber, a much-needed respite from the otherwise stagnant supply, although the north vent does not execute its task as well, being severed for a short distance within the excavated section ......” (Lepre 1990: 97)

Clearly, the dual-shaft system was capable of temporally ventilating the chamber, but it's uncertain a large funerary cortege ever went as far as the sarcophagus chamber as the valley temple and the cult centre on the east side of the pyramid were far more suitable venues for the funerary ceremonies.

Although in theory at least, its possible the shafts had a purely practical function, it is also possible the shafts had a metaphysical function related to the king’s afterlife beliefs.

Stephen Quirke: "The importance of the starry sky also seems clear in the positioning of narrow shafts, through the masonry core, from the inner chambers of the GP. Whatever their practical application as air vents, these are far too carefully incorporated into the design to escape symbolic significance" (Quirke 2001: 115-6)

The life-giving north and south winds blowing through the shafts may have had a role to play in Khufu’s afterlife allowing him to breathe "the air of his abundance":

Because the abomination of Summoner, the doorkeeper of Osiris, is ferrying without a toll having been paid to him, he will find a fare for himself and thus receive for himself his air of life. He will inhale happiness and become sated with god’s offerings: when he has breathed the air of his abundance, the north wind, he will become sated among the gods. P 450

Since you are the one who prevents them from slipping from within your arms, you should take hold of them, in your identity of the north wind; P 52

You will receive your two hands of the north wind and become verdant in the wake of the north wind, father Nemtiemzaf Merenre. M 365

Then the Sokar-boat, the pure gold of Him of the Sokar-boat, will be fetched for you, and you will be made to fly in it, and you will be made to fly in it. [For] the south wind will be your nurturer and the north wind will be your nurse. N 347

Teti has come to you, Enduring One. You shall turn back to Teti [like] the east wind [will turn back] in the west wind’s wake, you shall come in Teti’s wake like the north wind’s coming in the south wind’s wake. T 153

ba-shafts - link

Chris Tedder, autumn 2009