Kendall and Moran, in introducing their book on Geometrical Probability (Griffin, 1963), give as illustrations three solutions of a problem due to Bertrand, that of finding the probability that a “random chord” of a circle is longer than the side of the inscribed equilateral triangle. The first solution regards the random chord as being generated by the two points on the circumference which it joins, and which are uniformly and independently distributed. In the second the chord is assumed to have a fixed direction perpendicular to a given diameter, and its point of intersection with this is uniformly distributed over the diameter. In the third, the foot of the perpendicular from the centre is uniformly distributed over the circle. The probabilities in these three cases are respectively ⅓, ½, and ¼.