Considers the significance of observations on the Isle of Lewis. These concern the alignments of cairns and the concurrence of resulting lines at certan special points. With suitable definition of errors of alignments and concurrence, the probability distributions and expected numbers of these alignments and concurrences within a given error tolerance and arising from a random distribution of cairns are estimated. In particular the number of 7-line concurrences needed for statistical significance is calculated for appropriate error tolerances andnumbers of cairns. -- AATA