The treatments of the observations of short period are necessary often for tidal stereams and sometimes for tides. In the present paper some methods for extraction of harmonie constants from short period observations are suggested on the foundation of the quasi-harmonic expression(2) or(3)。 Method 1 or 2 deals with the observational series, which consists of several sets each of them including 24 records at hourly intervals. Both methods use Doodson's hourly multipliers (4) to separate the species 1, 2 and 4 for each set, then the least squares method is applied for determining the harmonic constants.