  Previous studies on the stellar content of the two nearby dwarf galaxies
NGC147 and NGC185 reveal a rich population of late-type giants in both systems,
including a large number of carbon-rich objects. These stars are known to show
pronounced photometric variability, which can be used for a more detailed
characterisation of these highly evolved stars. Owing to their well-studied
parameters, these Local Group members are ideal candidates for comparative
studies. Trough photometric monitoring, we attempt to provide a catalogue of
long-period variables (LPVs), including Mira variables, semi-regular variables,
and even irregular variables in NGC 147 and NGC185. We investigate the light
variations and compare the characteristics of these two LPV populations with
the results found for other galaxies such as the LMC. We carried out
time-series photometry in the i-band of the two target galaxies with the Nordic
Optical Telescope (NOT), covering a time span of \approx2.5 years. These data
were then combined with single-epoch K-band photometry, also obtained with the
NOT. Narrow-band photometry data from the literature was used to distinguish
between O-rich and C-rich stars. We report the detection of 513 LPVs in NGC185
and 213 LPVs in NGC147, showing i-amplitudes of up to \approx 2mag and periods
ranging between 90 and 800 days. The period-luminosity diagram for each of our
target galaxies exhibits a well populated sequence of fundamental mode
pulsators. The resulting period-luminosity relations we obtained are compared
to relations from the literature. We discuss the universality of those
relations because of which, as a side result, a correction of the distance
modulus of NGC185 may be necessary. Only one of our two galaxies, namely
NGC185, has a significant fraction of possibly first overtone pulsators. An
interpretation of this finding in terms of differences in the star-formation
histories is suggested.
