A new eight-dimensional conformal gauging solves the auxiliary field p
roblem and eliminates unphysical size change from Weyl's electromagnet
ic theory. We derive the Maurer-Cartan structure equations and find th
e zero curvature solutions for the conformal connection. By showing th
at every one-particle Hamiltonian generates the structure equations we
establish a correspondence between phase space and the eight-dimensio
nal base space, and between the action and the integral of the Weyl ve
ctor. Applying the correspondence to generic flat solutions yields the
Lorentz force law, the form and gauge dependence of the electromagnet
ic vector potential and minimal coupling. The dynamics found for these
flat solutions applies locally in generic spaces. We then provide nec
essary and sufficient curvature constraints for general curved eight-d
imensional geometries to be in 1-1 correspondence with four-dimensiona
l Einstein-Maxwell space-times, based on a vector space isomorphism be
tween the extra four dimensions and the Riemannian tangent space. Desp
ite part of the Weyl vector serving as the electromagnetic vector pote
ntial, the entire class of geometries has vanishing dilation, thereby
providing a consistent unified geometric theory of gravitation and ele
ctromagnetism. In concluding, we give a concise discussion of observab
ility of the extra dimensions. (C) 1998 American Institute of Physics.