The Sun's interplanetary magnetic field and the solar wind modulate th
e distribution of galactic cosmic-ray particles in the heliosphere. Th
e particles diffuse inward, convect outward and have drifts in the mot
ion of their gyro-centres. Irregularities in the IMF also scatter part
icles from their gyro-orbits. These processes are the components of so
lar modulation and produce streaming (and higher-order anisotropies) o
f particles in the heliosphere. The anisotropies can be investigated a
t the Earth by examining the count rates of cosmic-ray detectors. The
anisotropic streams appear as diurnal variations in solar and sidereal
time in the count rates. Higher-order anisotropies produce generally
much smaller semi-diurnal and higher-order variations. Theoretical mod
els of solar modulation predict effects that depend on the polarity of
the Sun's magnetic dipole. The solar diurnal and north-south anisotro
pies can be used to test these predictions. This paper is a short revi
ew of analyses of 60 years of cosmic-ray data collected at the Earth f
or the solar and sidereal diurnal variations present. Past analyses ha
ve yielded interesting and controversial results regarding the rigidit
y spectra and components of these anisotropies. Some of the controvers
y remains today. Analyses of these anisotropies have also yielded quan
titative information about parameters important to solar modulation, s
uch as latitudinal and radial density gradients. The relatively new te
chniques used for these determinations are explained here. Calculation
s of these modulation parameters from Earth-based cosmic-ray detectors
are reviewed and compared to spaceprobe measurements and theoretical
predictions of their values. Recently, investigations of the sidereal
and solar diurnal anisotropies have been combined to calculate mean-fr
ee-paths of cosmic rays in the heliosphere. The latest conclusions fro
m these analyses are that the parallel mean-free-paths of cosmic rays
may depend on the polarity of the Sun's magnetic field. The results of
these investigations are included in this paper to indicate the prese
nt state of knowledge concerning this facet of cosmic-ray research.