Integral representation for Maxwell´s equations with arbitrary time dependence

Integral expressions are presented for the fields inside a sourcefree homogeneous volume, in terms of the tangential electric and magnetic fields on the surface of the volume. Although this integral representation is available by straightforward methods, to the best of the author´s knowledge it has not appeared before, and it is much simpler than some. The representation also constitutes a statement of Huyghens´s principle for electromagnetic waves, in the sense that the contribution from each surface element is itself a solution of Maxwell´s equations. The relationships between this and previous representations are also pointed out.