Physical pictures: Engineering models circa 1914 and in Wittgenstein's "Tractatus"

Today I want to talk about an element in the milieu in which Ludwig Wittgenstein conceived the Tractatus Logico-Philosophicus that has not been recognized to date: the generalization of the methodology of experimental scale models that occurred just about the time he was writing it. I find it very helpful to keep in mind how this kind of model portrays when reading the Tractatus — in particular, when reading the statements about pictures and models, such as: That a picture is a fact (TLP 2.141 1), That a picture is a model of reality (TLP 2.12), That the “pictorial relationship” that makes a picture a picture is part of that picture (TLP 2.1.5.3), and That a picture must have its pictorial form in common with reality in order to able to depict it (TLP 2.17).