Context :

Aims : 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 Å line with the EUV Imaging Spectrometer ( EIS ) onboard Hinode .
A new application of coronal seismology is provided based on this observation .

Methods : We analyzed the EIS sit-and-stare mode observation of oscillations using the running difference and wavelet techniques .

Results : Two harmonics with periods of 12 and 25 min are detected .
We measured the Doppler shift amplitude of 1 - 2 km s ^ { -1 } , the relative intensity amplitude of 3 % - 5 % and the apparent propagation speed of 100 - 120 km s ^ { -1 } .

Conclusions : 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 ^ { \circ } , a true propagation speed of 128 \pm 25 km s ^ { -1 } and a temperature of 0.7 \pm 0.3 MK near the loop ’ s footpoint from our measurements .