  This work is devoted to investigation of low frequency variations in Polar
motion (PM). It has been shown that the main PM features can be effectively
investigated using not only time series of the Pole coordinates, but also using
series of latitude variations obtained from observations at one observatory.
Such an approach allows us to increase the length of observation series
available for analysis. In our study, we extended the IERS PM series back to
1840. We investigate trends and (quasi) harmonic oscilla-tions with periods
from one year to decades. The main results were obtained making use of the
Singular Spectrum Analysis. Other methods were also used for specific analysis
and independent check. The most interesting results are detection of two new
large phase jumps in the 1840s and 2000s, and revealing of 80-year period in
the PM variations.
