Moving Large Objects

Moving Large Objects: "Moving large stones over land was more involved. Sledges and rollers (the latter being of a more limited value) were available in pharaonic times, and workers were in great supply. Friction was the main obstacle. An 800 ton block measuring 4x4x20 m would create a ground pressure of 1 kg over each square centimeter of its base. A force of at least 400 tons would be required to overcome the friction. Modern engineers working under primitive conditions found that, while moving blocks weighing 6 tons on a sledge, friction could be reduced to nearly zero by wetting the track with a lubricant (in this case, water). In the relief pictured above, from the tomb of Djehutihotep, a man can be seen on the leading end of the sledge pouring a liquid on the ground in front of it. Modern reenactments also demonstrated that a friction 'seal' is formed beneath a static load that is broken when the load begins to move. An Assyrian relief (below) shows the use of a lever at the back of the sledge, possibly used to break such a 'seal,' or perhaps to propel it forward."