  A mathematical derivation of Maxwell's equations for gravitation, based on a
mathematical proof of Faraday's Law, is presented. The theory provides a
linear, relativistic Lagrangian field theory of gravity in a weak field, and
paves the way to a better understanding of the structure of the energy-momentum
tensor in the Einstein Field Equations. Hence it is directly relevant to
problems in modern cosmology.
  The derivation, independent of the perturbation theory of Einstein's
equations, puts the gravitational and electromagnetic fields on an equal
footing for weak fields, contrary to generally held views. The historical
objections to a linear Lorentz invariant field theory of gravity are refuted
for weak fields.
