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The century long (1914-2007) $H_{\alpha}$ (656.28 nm) spectroheliograms fromKodaikanal Solar Observatory (KSO) have been recently digitised. Using thesenewly calibrated, processed images we study the evolution of dark elongated ondisk structures called filaments, potential representatives of magneticactivities on the Sun. To our knowledge this is the oldest uniform digitiseddataset with daily images available today in $H_{\alpha}$. We generateCarrington maps for entire time duration and try to find the correspondenceswith maps of same rotation from Ca II K KSO data. Filaments are segmented fromCarrington maps using a semi-automated technique and are studied individuallyto extract their centroids and tilts. We plot the time-latitude distribution offilament centroids producing Butterfly diagram, which clearly shows presence ofpoleward migration. We separate polar filaments for each cycle and try toestimate the delay between the polar filament number cycle and sunspot numbercycle peaks. We correlate this delay with the same between polar reversal andsunspot number maxima. This provides new insight on the role of polar filamentson polar reversal.

Long term study of the solar filaments from the Synoptic Maps as derived from $H_{\alpha}$ Spectroheliograms of Kodaikanal Observatory