Re: Information & Power /Alexandria library

Spike Jones (spike66@ibm.net)
Tue, 04 May 1999 21:02:24 -0700

Anders Sandberg wrote:

> Most of the texts of the great library were likely copies of the
> Illiad and Odyssey. By all accounts there were a great redundancy...

I can knock out my own argument I proposed last week: that there was probably no technology in the great library that we have not greatly exceeded. I thought of an honest to Greek gods *technology* that they had, that we do not have now: how to make stone arches.

Today stone arches are approximated. Usually they are fake: the arch is made of cement with fake lines drawn in the wet facade.

Consider this, those of you who are mechanically inclined. Draw an arch. Put in lines perpendicular to the arch that describe a number of wedge shaped stones. Challenge: draw the lines in such a way that each stone is in pure compression (no part of the stone may be in bending moment) and there is no shear force at the interfaces between the stones.

Another way to state the problem is this: shape your stones such that the force vectors from the adjacent stones exactly equals the gravitation
vector. Obviously, the included angle in the top stone would be larger than the stone that whose centerline is 30 degrees from horizontal. In fact, the included angle of each stone is different from all the rest.

Can you calculate all the included angles without your computer? Can you calculate them *with* your computer? Evidently the Greeks knew how to do these stone arches.

spikus jonicus