What would gothic cathedrals have looked like if the groin vault had, like concrete, been lost as a technology at the end of the Roman Empire? That was last week’s discussion question in my Big and Tall seminar, and the class responded with some intriguing possibilities.
The alternate history has been a go-to question in the course since I started teaching it, since it highlights the evolutionary nature of building. Developments such as the groin vault, or wrought iron, or plate glass, all solved individual problems, but there would, undoubtedly, have been work-arounds that would have produced viable buildings solving functional issues in other ways. (Somewhere, in an alternate universe, a Big and Tall course is wondering whether humans would have built sky-dwellings without the discovery of Unobtanium. Submit your answers in the comments below).
Lots of good thoughts, including souped-up barrel vaults like those above. In the first case the assumption is that the flying buttress still develops, but it turns into a thicker element that can absorb more of the distributed thrust of the barrel vault, instead of just taking the point loads of a groin vault. The solution just above uses barrel vaults to thrust against one another (or, at least, against the supporting walls), and cleverly steps them down toward the ground to create a pyramid of perpendicular buttressing.
Less spectacular but perhaps more viable, a number of solutions involved more elaborate timber structures, trusses that adopted the pointed arch (imported from the middle east via Norman conquest and diffusion through the Mediterranean) and the availability of heavy timber in northern Europe. This makes perfect sense–if the groin vault never develops, just don’t build the groin vaults, but let the truss work that supports the tall timber roof express itself to the nave below.
OR, build simple trusses over masonry walls, but then find a way to build the Aya Sophia’s dome over the crossing–focusing your constructive energy on the church’s most sacred point. I like this one a lot–even though it would have been asking quite a bit of medieval carpenters to figure out that junction between dome and truss (something, let’s face it, that even Palladio couldn’t quite handle).
Thanks to Tyler Vincent, Jeffrey Klynsma, Obishek Mandal, and Phil Hess for some particularly striking suggestions. More alt-SciTech when we hit the age of iron…