Splicing apparatus for joining the paper web from successive reels in a cigarette or cigarette filter rod making machine includes provision for running each reel closer to the end in a controlled manner to reduce wastage of paper. For that purpose the diameter of the in-use reel may be monitored by an arm coupled to an electrical detector with an averaging or smoothing circuit so that a signal is obtained which is insensitive to reel non-circularity or eccentricity. Alternatively the end of the paper may be detected as a result of the loss of tension in the paper.