  We report the first observation of multiple-periodic propagating disturbances
along a fan-like coronal structure simultaneously detected in both intensity
and Doppler shift in the Fe XII 195 A line with the EUV Imaging Spectrometer
(EIS) onboard Hinode. A new application of coronal seismology is provided based
on this observation. We analyzed the EIS sit-and-stare mode observation of
oscillations using the running difference and wavelet techniques. Two harmonics
with periods of 12 and 25 min are detected. We measured the Doppler shift
amplitude of 1-2 km/s, the relative intensity amplitude of 3%-5% and the
apparent propagation speed of 100-120 km/s. The amplitude relationship between
intensity and Doppler shift oscillations provides convincing evidence that
these propagating features are a manifestation of slow magnetoacoustic waves.
Detection lengths (over which the waves are visible) of the 25 min wave are
about 70-90 Mm, much longer than those of the 5 min wave previously detected by
TRACE. This difference may be explained by the dependence of damping length on
the wave period for thermal conduction. Based on a linear wave theory, we
derive an inclination of the magnetic field to the line-of-sight about 59$\pm$8
deg, a true propagation speed of 128$\pm$25 km/s and a temperature of
0.7$\pm$0.3 MK near the loop's footpoint from our measurements.
