Experimental Investigation on a Full-Scale Replica of the Closing Mechanism in Cheops’ Antechamber

Cheops' Antechamber experiment (photo by C. Nguyen)

The antechamber in the Great Pyramid allows for a very close reconstruction of the closing mechanism because every important technical feature is well preserved. Such a reconstruction provides important insights into one of the key technologies of the time: The delicate placing of heavy blocks by lowering them into position with ropes. This task was performed many times, especially when constructing burial chambers, temple interiors, and even the façades of pyramids. The remains of many “lifting/lowering” bosses on heavy blocks bear witness to this.

Cheops' Antechamber experiment movies: bottom position (left), top position (right)

Only a full-scale reconstruction enables accurate results, because the local contact mechanics between ropes and blocks, ropes and timbers and blocks and walls depends heavily on the forces acting in these contact zones. Thus, realistic results can only be expected when the weight of the blocks is realistic, requiring them to be full-scale.

With the actual rope configuration unknown, we investigated a number of possible configurations to gain insight into their principal behaviour and identify the configurations that were most likely. We devised a system that allowed us to measure the force at the end of each rope. This enabled us to determine the number of persons necessary to operate the mechanism. Single rope forces are only between 500 N (non-lubricated) and 900 N (lubricated) for releasing a single block. This is mainly due to friction between rope and block. Therefore, one person can control two ropes easily with a simple control “knot” and two persons can lower a single block easily and smoothly.

Lowering all three blocks in sequence with one rope configuration presents a challenge: The 1stblock must be held back, the 2ndblock almost moves alone and the last block is difficult to control. It is a delicate process that takes precise placement of ropes, correct lubrication and experience of the two operators. When mastered, a total of 7,5 tonnes are lowered smoothly within a minute and almost without a sound: a solemn act befitting the final closing of the burial chamber for the man who was the reincarnation of Horus during his reign.