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 oscillations 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.