Juxtaposition

How about something from the 20th century, the 18th century and the 1st century in the same photo? If you travel to places like Segovia, Spain, that's not hard to come by.The Roman aqueduct that dominates that photo is the oldest structure seen here, though it is in amazingly good shape - especially since only gravity holds this structure up. That's right, there's no cement!So the question is: If the aqueduct is made of carefully carved and aligned stacked stone, how do the build the arches? In other words, since the last stone in the arch to go in is the one at the stop (the keystone) how do they keep the other stones in place before placing it?

Arches Gone Wild!

Today's post features a detail photo of some of the stone work in the Cathedral in Seville, Spain. Why "Wild" in the title? As you will see in Monday's post, the Roman arch was round and utilitarian. A thousand years later someone in western Europe decided to enhance the look a little. And the so-called "Gothic" arch was invented. It's main feature is that it is somewhat pointed at the top. The other feature is that medieval stone masons, without the benefit of sophisticated math and computer modeling, were able to make whole ceilings out of arched stone. And while they were at it, the dressed up the stone with elaborate carvings.The carvings add nothing structural to the arch. But they do look nice!