  We construct an electrical-network version of the twist map for the positive
Grassmannian, and use it to solve the inverse problem of recovering
conductances from the response matrix. Each conductance is expressed as a
biratio of Pfaffians as in the inverse map of Kenyon and Wilson; however, our
Pfaffians are the more canonical $B$ variables instead of their tripod
variables, and are coordinates on the positive orthogonal Grassmannian studied
by Henriques and Speyer.
