C Wayne Taylor Wrote:
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> Hi Graham,
>
> I think the builders would have performed surveys
> in much the same way surveyors do today.

I believe you are on the right track.

> From an orgin, establish a base line by sighting
> from the orgin to a distant point (eg. celestial)
> several times and take the average of the
> deviations. Then measure along the line with a
> calibrated chain or rod. If the surface is very
> smooth and level, the measurements can be made on
> the surface. If the surface is not level or is
> rough, plumb bobs at each end of the leveled
> device would be used--just as today. The distance
> could be measured several times to establish a
> mean. To turn a right-angle, a large T-square
> could be used to sight along the existing line and
> to sight the 90 degree line. The T-square could
> be flipped over and the process repeated several
> times to establish a mean bearing.

Ummh ... I dunno about that.

> The topography at Giza is not difficult. I think
> the main challenge would be clearing away sand to
> get down to a stable surface to set points.

Maybe it's not necessary to have flat surfaces.

Some years ago while walking through park land I came upon a grid of steel posts (star posts). I stopped to view the handy-work which had been set out for the nursery man to plant trees. It reminded me of driving past a pine plantation where you get this uncanny feeling of mechanical precision swishing by. The star posts however were even better for whoever laid out the grid surely had 20/20 vision. They weren't all perfect but there were some long rows of over 500 feet that I couldn't fault. Standing back for a better view these long rows appeared as one post. The ground wasn't level so the "one post" gained height.

I had seen all this before with 12 inch fencing posts over a great distance. The fencer's tool was a beer bottle placed on a far distant post which glinted in the sun. He filled in between with keen eyesight. It was a marvel to behold.

I don't have any problem with long straight lines. The really tricky bit is laying out pre-determined lengths. As I mentioned in a previous post the end on end rod is a non starter. Experiments have been done and if you take the mean you are always wrong. Putting it bluntly it's an impossible task over distance.

What's wrong with straight lines, good eyesight, maths and geometry? The geometry being the more important aspect. Surveyors understand that but here we are dealing with primitive surveying and probably to us, an unconventional process.

Graham