  We set up simple harmonic lattice models for elastic fluctuations in bcc and
fcc lattices and the excitation of dislocations and disclinations. From these
we derive, in a lowest approximation, universal formulas which predict melting
temperatures in good agreement with the experiments. This new theory is more
precise than Lindemann's rule by factor 2, and more predictive, since the size
of the Lindemann number has to be fixed by experiments. In addition, our theory
allows for systematic improvements.
