If I were given the job and the resources to do it, what better way than to use water?

1. They obviously had the shipbuilding technology to transport such items, so they could reverse this procedure and build a dry dock at the site.
   
   
2. Provide the monolith with flotation collars at optional locations. The collar should be located at just overcenter (lengthwise) and the secondary flotation collar located toward the base.
   
   
3. Close the container and fill it with water and when the desired elevation is achieved, flood the base.
   
   

Dennis Scott-Jackson
Burnaby, British Columbia

Dennis, the Egyptians were really great at building canals and dams, but they seem to be lacking in putting all the hydraulics into transferring water from one place to another. It's doubtful that they would have been filling chambers with water. To use this flotation idea, they would have had to have mastered moving great quantities of water, because no matter what they built it would have leaked quite rapidly.

I read your dispatch about the pulling progress. (See 'Pulling Together'.) If the pullers cannot maintain the dragging, then maybe the approach is just a few feet at a time. Try anchoring the ends of the ropes, then attach ropes to the middle and pull perpendicular. You increase your mechanical advantage. Your advantage finally drops to just 2X when the ropes hit 30 degrees from the direction you are trying to pull (at 10 degrees it's more than a 5X advantage, 20 degrees it's 3X—try the math).

Andrew Kulich
Rochester, Minnesota

Andrew, I agree with you that there is a lot of mechanical advantages to pulling rope perpendicular, but in my own personal opinion, I believe that they only pulled the obelisks very short distances. They would bring the obelisk by boat as close as possible and then they would have probably used rollers and a very firm rope—a combination of rollers and levers and rope—pulling—because it's a little easier to control. If you're depending entirely on ropes, they can act unfavorably at times.

After carefully observing the obelisk, it seems as if it was carved after being raised. It is very possibly easier to raise the obelisk in an "un-careful" state (not wanting to damage the carving) using a vertical drop. Being pulled carefully by rope over the drop (as seen in many Egyptian demonstrations), the obelisk would be pulled and standing at a vertical state.

(name witheld by request)

It's always best when you're carving into a block of granite to be working on the flat. So, it's probably likely that they did the carvings and rotated it on the ground. On the vertical, you could do some changes there, but it requires a lot of staging and it's more difficult work when the granite is in a standing position. As for being careful, they would had to have been careful whether it was carved or uncarved, because they went to a lot of trouble to get that block of stone there.

You almost had it the first time. Why couldn't you raise it with oxen? I would suggest the A-frame to be tilted more towards the pulling team from the start or set up two shorter A-frames in a series.

(name witheld by request)

You are right. When the rest of the team did their first attempt, A-frames in series would have helped. However, when you consider the largest obelisks, the use of A-frames becomes less appealing. The forces involved require enormous frames. The key to using this technique is getting elevation height above the object and reducing the force required by tilting the obelisk to a steep angle first.

As far as I could tell from your program, the problem is essentially one of controlled descent. Two methods were used, and a combination of the two seems to be reasonable: A very steep ramp (steeper than that used in the program), with raised blocks built into the ramp that guide the sled in its descent. These blocks could even be placed at an angle or shaped for the purpose of catching and guiding the sled. It would seem that these blocks, or even the whole ramp structure, could be reused, so it's conceivable that most of the work that you would have to do in raising an obelisk would be a matter of fabricating stonework that the Egyptians had on hand from past projects.

Markers would have to be placed at the runway at the top of the ramp to guide the sled; the blocks that physically guide the sled will, of course, be buried in the sand used to control the descent of the sled. The sled would be pulled onto the bed of sand to the point of balance, the sand would be released, and the sled would slowly slide down the (very steep) ramp. The descent is controlled by a combination of sand removal and support ropes from behind. The bottom of the obelisk could be fitted into the turning groove in this manner. The sled runners, the height of the block, the location of the turning groove, and the base of the obelisk would have to all be coordinated, but this should not require any great feat of math (not that I pretend to be an expert in either math or the ancient Egyptians' grasp of it).

Anyway, setting the base of the obelisk, I believe, is a matter of a sand-controlled, block-guided descent down a very steep ramp to a pre-measured destination. The steeper the ramp, the better (I would guess), because this would put the obelisk at such an angle so that getting it upright would be easier.

Once this was done, many possibilities present themselves. A long structure could be built at a right angle from the top of the obelisk before it is erected: It would look like an inverted "L." The beam perpendicular to the obelisk would have to be supported from the end of the beam farthest from the obelisk to the base of the obelisk, creating a triangular structure laying against the side of the obelisk and attached to it; the widest part of the triangle at the top of the obelisk and a pointy end at the bottom. (The obelisk itself would form one of the longest sides of the triangle, with its base at the most acute angle of the triangle at the base of the obelisk.) I don't know if the Egyptians from that period understood the idea that a triangular brace will make a structure stronger, or if they had material which would make such a structure possible.

Assuming that such a structure is feasible, it would be attached to the obelisk before it was lowered into the pit. The obelisk would be lowered as before, and the sandpit would be disassembled around the obelisk and its attached structure once the sand was drained. Many ropes would be attached to the end of the beam perpendicular to the top of the obelisk on the end of the beam farthest from the obelisk.

Someone would then have to climb out onto the end of the beam and start hoisting up sandbags. As a practical touch, a little seat could be built onto the end of the beam for this purpose. This would add comfort and efficiency, because I contemplate a slow pace in this phase—about 10 to 20 pounds at a time. Since we are talking about such huge weights, this would take a good deal of time, but by the same reasoning, a platform with three men could work pretty steadily at the end of the beam.

This method would, of course, present the problem of enormous torsion at the base of the obelisk if the counterweight were not balanced along the midline of the obelisk. Also, if the whole contraption were not balanced properly, the structure would likely collapse; it is not built to take lateral strain in one direction. Lateral strain in two directions, however, would have the net effect of balancing the whole contraption. The balancing could be done in the following manner. Ropes would be placed like guy wires on each side if the obelisk and structure. These would be "paired" ropes, two ropes to each support. The ropes could then be twisted with large poles to control the lateral movement of the obelisk and the counterweight. Further, the ropes could be stretched over A-frames to make them more manageable. Someone could "eyeball" the structure from a distance, and with either runners or hand signals, fine-tune the raising of the obelisk.

The whole would, of course, have to be supported from behind in order to keep it from toppling forward once the counterweight went past the point of balance. These support ropes would be pre-twisted in a manner that the tension on them could be slowly released. Once the obelisk was upright, the sandbags would be cut away one by one, and the tension on the ropes slowly released, and the obelisk would be left standing once the structure was cut away from it.

A theoretically similar method to the above involves the use of A-frames. Instead of one A-frame, however, an array of A-frames would be used, much in the same manner as a very large team of horses is arrayed from a very heavy load. Some of the A-frames would be closer to the "load" and some would be farther away, but in the end, all would pull in the same purpose. Again, lateral guide ropes would be twisted to control lateral movement, and sandbags would be used to pull the A-frames.

I really think this would work. The ropes could be attached to the obelisk and then stretched over the A-frames. Sandbags could then be attached to the ends of the ropes after they are stretched over the A-frames. Again, the sandbags would be attached one at a time. A few bags could be attached in the beginning to make the A-frames stand up, and then two people could be stationed at each frame to hoist sand bags. Note that this would not require cruelly heavy labor on the part of anyone, and the methods used would be only moderately dangerous. Further, it would not require huge crews, and could be accomplished with about a hundred people (assuming that each frame can pull a ton).

The A-frames could probably not lift the whole obelisk at once, and would have to be moved several times in order to bring it all of the way up. The obelisk, of course, would have to be supported from behind each time it was lifted a little. This would probably change their relative positions, and they would have to be initially spaced so that they will not interfere with each other throughout the whole of the project. Again, the ascent of the obelisk would be controlled laterally and from behind with twisted ropes. Once the obelisk was upright, the sandbags would be slowly cut away from the A-frames and the tension on the ropes would be released.

To sum up, I would raise the obelisk by sand-controlled and block-guided descent down a very steep ramp and then use a large counterweight balanced by ropes to help in raising the obelisk. Or, I would use several A-frames to slowly pull the obelisk into position once it was placed in the turning groove by the controlled descent described above. Again, sand, and not brute human pulling power, would be used as both the force and control needed to raise the extremely heavy obelisk once it was in the turning groove.

Marcus Vise
New Orleans, Louisiana

The difficulty with the sand method is twofold. First, there is the size of the construction required to get the height of the ramp. Sandbanks are naturally at quite a shallow angle, and if it is banked up high enough for the big obelisks, the pile would cover an enormous area. I sometimes feel that the implications of this have not been considered. In the temples, monuments are closely spaced and all would be covered in sand during the erection of the latest obelisk.

The second difficulty with sandpits is control. How do you let sand out of a chamber evenly to avoid the obelisk going off course? We saw the difficulties on the last NOVA program, and that was with a tiny obelisk. A 'sand-box' has been suggested by some archaeologists. The suggestion has been that mudbrick was used to enclose the sand. I remain skeptical about the ability of mudbrick walls to resist the lateral pressures of the huge height of sand. Sand control makes sense to me for cuboid heavy objects like a sarcophagus or some statues, but not for the shape of the obelisk.

The raising methods you describe are all feasible from a steep angle. The reason I hesitate to use an A-frame to pull the obelisk the last few degrees to vertical is the risk of overturning the obelisk. It may be easier to pull in a less direct way at the front by 'swigging' (pulling horizontally on anchored vertical ropes) and brake the obelisk at the back to achieve fine control.

Why don't you use the sled and A-frame idea, but then use the sled to help push the obelisk up?

(name witheld by request)

There are two major problems with sliding the obelisk down a slope on its sled. First, you don't really have control. It is not so bad on a short obelisk as with the one used in the first NOVA Obelisk program, but getting the obelisk on line as it slides is very difficult. Second, pulling the obelisk up with an A-frame requires tremendous force, because you are working against the weight of the stone all the time. Just imagine the number of people required to pull up a 400-ton stone in this manner—you are talking about thousands of laborers!

I would first cut the thing from the bottom, then use a crane and a lever.

(name witheld by request)

I'm not sure what you mean by 'cut from the bottom,' but I presume you mean an ancient crane! In a sense, we will investigate ancient lifting gear when we try to pull the butt end of the obelisk down. By combining timber members in compression and rigging in tension, we have a type of crane system off the end of the obelisk, giving us additional leverage to rotate the obelisk.

Perhaps they dug canals to the spot where they wanted to put the stone and brought it there from quarries by the river, by raft, and then dug a deep hole at the end of the small canal, and slid the obelisk off the raft and in to the deep hole while pulling on it with ropes, then filling up the canal and holding the stone in place until the earth dried—just a thought.


Austin, TX

Well, rafts are not suitable, because the amount of buoyancy available on a raft isn't sufficient—even in a big raft—to float an obelisk weighing, say, 300 tons. There has to be a boat or combination of boats. Then it's necessary to work out how they actually loaded the boats. The big problem, of course, is stability. Having no cranes, what method did they use? We hope to show that here in Egypt in the next few days.

Your Q&As lead me to two suggestions and one observation:

1. The first technique refines the pivot approach. Use rollers to move up a ramp to the height of the center of gravity, with the lower portion extending off the end. The outsides and end of the ramp should project forward on each side of the base and be stone-reinforced, leaving a clear vertical column. Attach a pivot at center of gravity, which should be over the clear column. Hang 'baskets' at each end of the obelisk with rocks for counterbalancing. Gradually shift the rocks, using ropes for control as the shifting weights do the moving. Resulting operation looks like a balance with the obelisk as the beam. (Depends on a strong pivot.)
   
   
2. Using the A-frame with pullers' ropes at the top and ropes to the obelisk at the cross beam: use two or three frames in a row to multiply the leverage, working off a ramp significantly higher and opposite the obelisk's. Pull, brace, shorten rope to obelisk; repeat.
   
   
3. Observation: the large projects such as a pyramid would have done far more than binding the nation through socialization during the period of 'draft' labor. It would have created a national language: reinforcing a 'governmental version' over dialects from remote areas; and bringing in minorities speaking other languages altogether. It also would have served as a schooling system with practical applications of writing, calculating, and engineering techniques, which would have increased commerce and the living standard. The resultant prosperity would have been a magnet to outlying peoples (such as the Israelites). The newcomers would, in turn, contribute additional knowledge, manpower, and demand, accelerating the growth.
   
   

Karl Veit
Washington, DC

The suggestion incorporates the principles of what we are trying to do in this experiment. (See 'Second Chance'.) We are attempting to use the weight of the obelisk to our advantage by pivoting it close to the center of gravity (CG). The problem with pivoting the stone exactly about its CG is that as soon as rotation begins, the CG is beyond the pivot and the obelisk wants to move on its own. This is difficult to control!

1. That's why we are placing the pivot in front of the CG so that we can rotate it to about 60 degrees before the obelisk wants to rotate on its own. At 60 percent the free rotation is easier to control. To pull the butt end of the obelisk down to get rotation, we can use two methods. The first is by using counterweights as you suggest. The second is to use men pulling horizontally on vertical ropes attached to the butt end as described by Mark Whitby in the e-mail with Andrew Kulich below.
   
   
2. The problem with A-frames is both the strength of the A-frame itself and also the number of people required to pull. Many obelisks are placed in pairs, meaning that there is no space to locate a run-off ramp beyond the obelisk for the A-frames. This would need to be positioned where the first obelisk is already standing.
   
   
3. One of the biggest lessons learned from the pulling exercise yesterday is how important organization of labor is on an operation like this. There can be little doubt that the workers, even those simply tasked with pulling on ropes, would have been well drilled and very skilled at what they were asked to do. Also, the chain of command and communication are vital in such a tricky operation. For example, you mention language. This is a major factor in our experiment. The translation between English and Arabic takes time, when decisions are often being made in split seconds. For the raising, we are considering using colored flags for certain key commands to speed up the communication.
   
   

Why not tie wood to the sides of the obelisk and divert the Nile and float it to the place it needs to go and plop it in the hole?

(name witheld by request)

This question has the same problem as the one about floating it on a raft (see above). You just wouldn't be able to tie enough wood to the obelisk to float it. It would have to be a boat.

The method for raising an obelisk would work the same way as we developed for another primitive, though modern-day monument raising in the desert, Burning Man. The technique we employ to raise our annual one-ton, 40-foot rigid monolithic structure on a flat plane, from horizontal to vertical, using human power and age-old technology, is a lever. This form of lever we call a boom.

Materials needed for proposed obelisk raising: rope, wood, people.

With obelisk lying on ground, build a four-legged tower the height of the obelisk, just in front of the base end. The tower will have to be sturdy enough that the front two legs will be able to support half the weight of the obelisk. Haul rope, strong enough to lift over half the obelisk's weight Ð or several ropes that sum equal strength—over the top of the tower and attach to the top end of the obelisk. The length of the rope—to be determined by how many people are spaced along it to pull half the weight of the obelisk—is fed in the opposite direction. Four guide ropes are needed: one on each side to prevent sideways swinging: one from the rear to keep from toppling forward: and one spanning from the top end of the obelisk to the top of the tower. With this last guide rope in place, remove the back two legs of the tower, allowing the tower to pivot downward as the obelisk raises.

With our boom-lever system in place, we now need only enough people to pull the weight of less than half of the obelisk (remember we're lifting the skinny end). The number of people could be further reduced by using counter-weighting and multiple booms or block-and-tackle pulleys.

Dan Miller
San Francisco, CA

This is an interesting way of doing it. The problem is that if an obelisk weighs 200 tons, you're saying you're going to have to pull over 100 tons. Now, the first thing is that the tower is as tall as the obelisk, so the angle up the side of the rope you're pulling is at 45 degrees. Forty-five degrees means you've got root 2 of the weight of the obelisk, which is 1.3. So, the 100 tons of the obelisk is now multiplied up to 132 tons, which is the pulling force.

Now, the way we calculate the pulling force for a person is that, at maximum, a person can pull his own weight. At maximum, while pulling on a rope, he inclines himself at 45 degrees, puts his weight down vertically, and pushes with his feet. If he pushes too hard, the rope pulls them back up, and the only thing countering that is his weight. This is the theory we work on. So let's say that the weight of a person is 100 weight (112 pounds), which is a slight underestimation. There are 20 of those to the ton, so to pull 130 tons, you need 20 times 130, which is 2,600 people. This is why I think this method is a little bit questionable.

Also, if you took a very tall obelisk, and the height of that obelisk is such that the tower is pulling against it is going to have to be of an equal height—that again has its own issues, in that the structure you're building is an 80-foot tower made out of bits of timber. You'd have to make it strong—yes, all is possible in this day and age, but I'm not sure that necessarily they would have gone for that. The way we're looking at it, we're going to reduce the number of people down to 150, and maybe even less than that to pull this obelisk to vertical.

To increase the mechanical advantage of pulling ropes, skip the pulleys. You can achieve greater advantage by anchoring the end of two ropes and then pull the two ropes in the middle with equal force in opposite directions perpendicular (y-direction) to the direction you want to pull (x-direction). The force exerted in the x direction is equal to two times the y-direction force divided by the sine of the angle the ropes make to the x direction. The less of an angle you have, the greater of a force you direct in the x direction. So a few people pulling on ropes tied to the middle of the main pulling ropes can exert plenty of pulling power. Think of putting a small weight in the middle of a string, then try pulling the sting tight horizontally. No matter how hard you pull, you can never get the sting perfectly horizontal. The heavier the weight the harder you have to pull.

P.S. I thing it was a combination of the levers to get it started, Then the above with an A-frame to increase leverage is what they used.

Andrew Kulich
Rochester, Minnesota

The method described by Andrew Kulich is exactly what we're proposing. (See 'Second Chance'.) The principle is this: We've got the obelisk with the center of gravity slightly back from the pivot point. We will need to apply a load on the base end to upset it. The first pull will be the biggest one. We'll bring it down by pulling on a frame that is fixed to the butt-end of the obelisk and that extends out beyond the end. The frame, which is very similar to frames they have on boats, will be windlass-tight to begin with.

We will have four sets of ropes come down off the end of the frame, and those will be pulled in a direction perpendicular to the lie of the obelisk. We don't want to apply a horizontal force to the obelisk, or we run the danger of pulling the obelisk forward and pulling the pivot off its bearings. So we will pull it sideways, and we will actually get a six-to-one mechanical advantage.

We will windlass them tight—we will actually lash the windlass to the pulling rope—and we'll have another pair of ropes that we'll anchor down so the butt end comes down. We'll pull those back over a block and anchor them. Then we'll release the pair of ropes, which will allow a bit of recovery in the obelisk's position. Hopefully it won't go back to the beginning, otherwise we'll have gotten nowhere. And then we'll pull again. We'll always have a long length of rope to give us a maximum mechanical advantage.

As the system develops, and the center of gravity, which is behind the roller, rotates upwards and comes to a point where it's vertically over the roller, at that point the obelisk is in balance. Any further movement will mean that the obelisk will take over and move at its own accord. At that point we'll have to be really careful. That angle is why we've set the rotation point in the place we have. What we want to do is have it as near to vertical as possible. It is quite an interesting problem; it sets up the whole geometry for the height of the ramp and everything. From that point onwards, it doesn't matter how big an obelisk you're dealing with. That's the sort of arrangement you'd like to have, because it's all similar proportions.

Why not use a pulley on level ground to gain a mechanical advantage for the pullers?

Sent in by Travis

Well, we often get questions of why we don't use pulleys in pyramid-building or obelisk-raising, and one very critical piece of information here was given by Roger Hopkins on the production of "Obelisk." He said a pulley is only as good as a wheel is as good as its axle. In other words, they didn't have iron or steel at this period, and for a pulley really to work, you need a very strong axle. A pulley is essentially a wheel. For wooden pulleys or various other kinds of pulleys, it just didn't work. They probably had something like the pulley as early as the Middle Kingdom, several hundred years before the New Kingdom, but it was not as powerful as it would have been had they made it out of steel or iron.