  Project GRAND observes small variations in the number of incident muons when
plotted versus local solar time. The total accumulated number of muons by GRAND
over four years' time is ~140 billion. The data obtained by Project GRAND are
compared with data from neutron monitor stations at Climax and at Newark which
detect secondary neutrons. Project GRAND is an array of 64 proportional wire
chamber stations which are sensitive to secondary muons at energies greater
than 0.1 GeV. The mean energy of cosmic ray primaries which produce these muons
depends on the spectral index. For a differential spectral index of 2.4, the
most probable gamma ray primary energy is about 10 GeV, the response falling
steeply below this energy and slowly above this energy; this most probably
energy varies only slowly with spectral index.
