To demonstrate the mutual effect, we calculate the solution that satisfies only the second geometrical condition Eq. (22). The solution obtained is plotted on the Lg–SD plane in Fig. 5, in which the equivalent lengths of the ascending cable are also plotted. The curve of the solution is upward concave; the curve is downward to the right if Lg is more than 60 m and is upward to the right if Lg is less than 60 m. From the curve, we find that the length of the descending cable is maximum at Lg = 60 m.