Re: Information & Power /Alexandria library

Michael S. Lorrey (mike@lorrey.com)
Wed, 05 May 1999 08:57:30 -0400

Spike Jones wrote:

> 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.

I can state for a fact that this knowledge is not lost, only out of use due to its expense. In the late 1800's, John Rockefeller owned most of what is now Acadia National Park, on Mount Desert Island in Maine. He built several of his typical 'country cottages' of 100 rooms or more, and built 57 miles of carriage roads to ride his horses on. Every bridge along the carriage roads was built of hand hewn granite, just as was done by the greeks and romans. These are some of the most beautiful stone arch bridges you can find anywhere, but you will rarely find anyone today who will pay for such collossal wastes of money. Rockefeller is quoted as saying he might as well have built them out of diamonds, for all their cost.

Mike Lorrey