This page has a short description of medievel cathedral building. There is an interactive that lets you try your hand at stacking stones into an arch and resisting the resultant thrust, neat stuff.
http://www.pbs.org/wgbh/nova/physics/arch-physics.html

   Thanks, Don,  that is sooooo cool!  Medieval cathedrals are beautiful -- wonder how many times people got killed by the falling building blocks?

Somewhere (maybe here?) I read that, in Roman times, the architect had to stand underneath the arch as the keystone was laid -- talk about putting your money/body where your mouth/drawings is/are!


carroll

I don't know how many people "learned the hard way" but I'll bet it was more than a few. I have the report of a floor collapse in one from the 1500's, if memory serves, that killed many at the upper end of the social ladder.

I hadn't heard that about the roman architects...would kind of make a young engineer look into a career in road building  As long as I'm rambling, a tekton was a builder in ancient times, usually a stonemason. an arch tekton was a master builder... an architect. Joseph, Mary's husband, was described in early texts as a tekton, he was probably a stone mason rather than a carpenter.

Arches were actually built over a falsework, or form. When the keystone was set the falsework was removed, that would have been the tender moment. I think my memory is correct, in our country Ithiel Towne, the inventor of the towne lattice truss, a covered bridge, stood underneath when they knocked the props out from under his first one.

Back to cathedrals, the master builder would check the joints in the buttresses and pinnacles very often as the work progressed. Any telltale cracks in the mortar let him know he was going into tension... time to make the pinnacle a little taller.

   I love how much I learn on this site -- thanks, Don!  The idea of the 'arch tekton' standing under his arch may have come from my Earthbag Shelters book -- I'll try and find the reference (later -- too late tonight, that's for sure!)


carroll

   I had mine falling down as I perfected my learning curve.   

Years ago I did some reading on how the stone mason's art improved over the centuries. And still there are those who are reinventing the wheel, so to speak. Or perhaps some builders did not do the foundation preparatory work sufficiently well. Back home our church was a grand looking quarried limestone affair. Some seventy years after it was built the sidewalls were slowly being forced outwards. Not sure why for certain; maybe the foundation, maybe some inferior timber framing. Anyhow the engineered solution was a series of steel rods positioned across the width up near the top of the walls. Holes drilled through the stone with large steel plates on the exterior.