  For the solid-on-solid (SOS) model with spin values from the set of all
integers on a Cayley tree we give gradient Gibbs measures (GGMs). Such a
measure corresponds to a boundary law (which is an infinite-dimensional
vector-valued function defined on vertices of the Cayley tree) satisfying an
infinite system of functional equations. We give several concrete GGMs of
boundary laws which are independent from vertices of the Cayley tree and (as an
infinite-dimensional vector) have periodic, (non-)mirror symmetric coordinates.
