The non-local part of the gravitational field in general relativity is described by the 10 component conformal curvature tensor
C
abcd
of Weyl. For this field Lanczos found a tensor potential
L
abc
with 16 independent components. We can make
L
abc
have only 10 effective degrees of freedom by imposing the 6 gauge conditions
L
ab
s
:s
= 0. Both fields
C
abcd
,
L
abc
satisfy wave equations. The wave equation satisfied by
C
abcd
is nonlinear, even
in vacuo
. However, a linear
spinor
wave equation for the Lanczos potential has been found by Illge but no correct tensor wave equation for
L
abc
has yet been published. Here, we derive a correct tensor wave equation for
L
abc
and when it is simplified with the aid of some four-dimensional identities it is equivalent to Illge’s wave equation. We also show that the nonlinear spinor wave equation of Penrose for the Weyl field can be derived from Illge’s
spinor
wave equation. A set of analogues of well-known results of classical electromagnetic radiation theory can now be given. We indicate how a Green’s function approach to gravitational radiation could be based on our tensor wave equation, when a global study of space-time is attempted.