We have used sidereal diurnal variations observed by neutron monitors
and surface and underground muon telescopes to examine the north-south
anisotropy and radial density gradient of high-energy galactic cosmic
rays between 1957 and 1985. We have derived the average amplitude and
rigidity spectrum of the anisotropy for this period and estimate the
radial gradient to be best represented as a function of rigidity P by
1.02 x (P/10)(0.5)% AU(-1) for rigidities less than approximate to 450
GV. The temporal variation of both the north-south anisotropy and the
radial density gradient show a solar cycle variation. Possible depend
ence of the anisotropy on the solar magnetic polarity state has been e
xamined under the assumptions of a static and a nonstatic rigidity spe
ctrum, with conflicting results. We show that the analysis is affected
by a further sidereal variation and that the responsible anisotropy i
s related to the asymmetric heliospheric modulation of a galactic anis
otropy.