This report analyzes the I -band CCD photometry of Nova V1974 Cygni from the 1997 observational season .
The analysis shows that both short-term modulations with periods 0.0813 and 0.085 days are still present in the light curve of the star .
We confirmed the stability of the shorter period which is interpreted as the orbital period of the binary system .
Its value , determined using the O - C residuals , is P _ { orb } = 0.08125873 ( 23 ) days = 117.0126 ( 3 ) min .
The longer period , which appeared in the light curve in 1994 , was decreasing until the beginning of 1995 but then started to increase quite rapidly .
In October 1996 the value of the period was 122.67 \pm 0.02 min .
Until the next observing run the period significantly decreased .
Its value , determined from our observations performed in July 1997 , was 121.87 \pm 0.12 min .
This means that the rate of change of the period in 1996-1997 was as high as \dot { P } \approx 10 ^ { -6 } .
Such a rapid change of the period requires a large amount of rotational kinetic energy , if we assume that a 122-min periodicity is the rotation period of a white dwarf .
Thus the more probable explanation is the hypothesis is that the longer period including a superhump period is caused by the precession of an accretion disc surrounding a white dwarf primary .

Key words : Stars : individual : V1974 Cyg – binaries : close – novae , cataclysmic variables