This only concerns the float of the first floor, that of the subterranean chamber.

When the water level in the water circuit is higher than the well shaft, where the float is, can hold, an impermeability between the float and the well shaft’s walls needs to be installed. If not, the water in the circuit will flow out of the circuit and into the access gallery for the stones.

Guaranteeing the float’s watertightness is as good as turning the float into a piston, as only its top part can be in contact with water while the rest is exposed to air and no longer needs to be watertight.

Yet, the well shaft is 36 meters long and might be fine masonry, as we can notice it on the casing of the pyramid or inside the Upper Chamber of Cheops, but can it really provide a contact surface flat enough between the moving float and the wall for it to move without water infiltrating it? I highly doubt that.

The only solution that comes to mind, and that complies with the five criteria of the pyramid, which are audacity, simplicity, efficiency, reliability and low cost, is to close the cylinder with a membrane, like a kind of sock, that is fixed at the bottom of the well shaft in a way to ensure impermeability, large enough to contain the float, and made to keep, at the same time, pressing against the wall of the well shaft and against the float as it goes up and down.

Waterproof sock

A membrane made of a fabric, that resembles that of skins, is not completely watertight, but it only lets slip through a minimal amount of water, which is sufficient to guarantee water tightness.

By leaving a slack of a few centimeters between the float and the well shaft on each side, the membrane will, under the effect of pressure, press against the float, wrapping it, and against the well shaft’s wall. As a result, the membrane suffers no stress on these contact surfaces.

Membrane wrapping the float

The cross-section of the float, and therefore of the well shaft, had to be circular to avoid the factory turning back on an angle, which would have led to premature wear.

The only area of the membrane subjected to pressure is the part located in the float/well slack, which can be, for example, 5 cm (1.96 in.) wide, i.e., a surface area of 5 cm2 per cm of fabric perimeter around the float.

With the water level at its highest point at +21 m (68.89 ft.) and the half-height of the well at -18 m, the maximum pressure on the membrane is equivalent to a water column 39 m (127.95 ft.) high, resulting in a pressure of 39 N/cm2, which produces a tensile force on the fabric at the point where it comes into contact with the open air of around 200 N per cm length. This force is divided between the two sheets: the one pressed against the cylinder and the one pressed against the float, i.e., 100 N per cm of length, which the membrane fabric is designed to withstand. The fabric is not subjected to great stress and can resist for a long time.

In addition, the fabric is wetted and thus lubricated as it deforms during the slow movement of the float, which increases its longevity.

Over time, however, it will have to be replaced regularly as a wearing part.

That way, the water tightness between the float and well shaft is guaranteed without friction; all it takes is for the float to be guided inside the cage and its walls to be well flat, easy to obtain by masonry, thus avoiding any rough surface.

In this configuration, the oscillations of the float consume very little energy.

It should be remembered, however, that the float on the subterranean chamber would have moved back and forth some 4,000 times a day, and 20 million times over the duration of the project; no membrane can last that long.

This solution was reserved to lift megaliths with the subterranean chamber elevator to increase the elevator’s efficiency, i.e., when it comes to the construction of 13-meter (42.65 ft.) high courses; otherwise, all other well shafts functioned without installing impermeability between the float and the well shaft.