<P> Levering methods are considered to be the most tenable solution to complement ramping methods, partially due to Herodotus's description; and partially to the Shadoof; an irrigation device first depicted in Egypt during the New Kingdom, and found concomitantly with the Old Kingdom in Mesopotamia . In Lehner's (1997: 222) point of view, levers should be employed to lift the top 3% of the material of the superstructure . It is important to note that the top 4% of this material comprises 1 / 3 of the total height of the monument . In other words, in Lehner's view, levers should be employed to lift a small amount of material and a great deal of vertical height of the monument . </P> <P> In the milieu of levering methods, there are those that lift the block incrementally, as in repeatedly prying up alternating sides of the block and inserting a wooden or stone shims to gradually move the stone up one course; and there are other methods that use a larger lever to move the block up one course in one lifting procedure . Since the discussion of construction techniques to lift the blocks attempts to resolve a gap in the archaeological and historical record with a plausible functional explanation, the following examples by Isler, Keable, and Hussey - Pailos list experimentally tested methods . Isler's method (1985, 1987) is an incremental method and, in the Nova experiment (1992), used wooden shims or cribbing . Isler was able to lift a block up one tier in approximately one hour and 30 minutes . Peter Hodges's and Julian Keable's method is similar to Isler's method and instead used small manufactured concrete blocks as shims, wooden pallets, and a pit where their experimental tests were performed . Keable was able to perform his method in approximately 2 minutes . Scott Hussey - Pailos's (2005) method uses a simple levering device to lift a block up a course in one movement . This method was tested with materials of less strength than historical analogs (tested with materials weaker than those available in ancient Egypt), a factor of safety of 2, and lifted a 2500 - pound block up one course in under a minute . This method is presented as a levering device to work complementary with Mark Lehner's idea of a combined ramp and levering techniques . </P> <P> Houdin's father was an architect who, in 1999, thought up a construction method that, it seemed to him, made more sense than any existing method proposed for the building of pyramids . To develop this hypothesis, Jean - Pierre Houdin, also an architect, gave up his job and set about drawing the first fully functional CAD architectural model of the Great Pyramid . His / their scheme involves the use of a regular external ramp to build the first 30% of the pyramid, with an "internal ramp" taking stones up beyond that height . The stones of the external ramp are re-cycled into the upper stories, thus explaining the otherwise puzzling lack of evidence for ramps . </P> <P> After 4 years working alone, Houdin was joined by a team of engineers from the French 3D software company Dassault Systemes, who used the most modern computer - aided design technology available to further refine and test the hypothesis, making it (according to Houdin) the only one proven to be a viable technique . In 2006 Houdin announced it in a book: Khufu: The Secrets Behind the Building of the Great Pyramid, and in 2008 he and Egyptologist Bob Brier wrote a second one: The Secret of the Great Pyramid </P>

What simple machines were used to build the great pyramids of giza