Dialect geography: isoglosses, distance-decay, and seriation

A chess piece can have a dialect boundary, just like a spoken language does. This page gathers conjectures that borrow a linguist's tool -- dialectology, which maps how a language feature changes across geography by drawing an isogloss, a line marking where one variant gives way to another -- and point it at objects that are not words at all: the geographic line where a chess piece's shape changes, the falling-off of Greek-language writing the further one travels up the Nile from its centers, even a provincial accent frozen into a knotted record far from where it was actually spoken.

Chess isoglosses and Bell isoglosses both draw a literal isogloss for a non-linguistic object -- where a chess piece or a bell's form changes from one type to another -- and test whether it coincides with a known cultural boundary. The Greek lapse rate fits an explicit decay curve to how quickly Greek-language documents thin out with distance up the Nile. Chant obeys the Speyer line and Neumes ride the rivers both test whether liturgical chant obeys a geographic frontier the same way ordinary dialect does, expecting two independent maps, of melody and of political boundary, to coincide if they really record the same underlying spread.