  We present results of four-color WBVR- photoelectric observations of the
close binary HZ~Her=HER~X-1 in 1986--1988. As a rule, the duration of the
observations exceeded two 35-day X-ray orbital periods in the 1986--1988
observing seasons. The accuracy and length of the photoelectric observations
facilitated multi-faceted studies, which enabled us to define several fine
photometric effects in the light curves of the binary more precisely and
attempt to interpret them in a model for the matter flow from the optical
component to the accretion disk around the neutron star. This model provides a
satisfactory explanation for the inhomogeneity of the gas flow and "hot spot",
as well as the existence of distinct "splashes" moving in their own Keplerian
orbits around the outer parts of the Keplerian disk. We present series of light
curves for all the observing seasons, as well as color--color diagrams that
reflect the physics of various photometric effects. The transformation
coefficients for each of the instrumental systems for the three observatories
at which the observations were carried out are given. Atmospheric extinction
was taken into account during multi-color observations of the object, with
subsequent correction for atmospheric effects with accuracies ranging from
0.003^m to 0.005^m for air masses up to M(z)=2.
