Three series of simultaneous wave and microseism records are examined. They give a clear indication that bands of microseismic waves from different sources can be distinguished by submitting seismograph records to frequency analysis. The agreement between the results of analysis and the theoretical expectation from the prevailing meteorological conditions appears to justify the assumption that microseismic waves of different periods travel independently. Under the simple meteorological conditions that have been studied, each band of microseismic activity can be identified with a band of sea waves of twice its period. The existence of this two to one ratio between the period of waves and microseisms affords some confirmation of the theory that microseisms are produced in a region of interference between similar wave trains travelling in opposite directions either near the coast or in deep water.