In general, simultaneous adjustment of leveling net which is composed of many loops is considered to give most plausible result. But, when one loop involves large error or closure, simultaneous adjustment not always gives standard result. In order to see the distribution of closure correction, some calculations are made using simple models of leveling net in this paper. In Fig. 1 (C), a method of representation of correction distribution is shown. All results of calculation are illustrated in Figs. 2, 3-1, 3-2 and 3-3. Using actual result of survey which was made in 19501952 (Table II), 9 cases of adjustment (in Fig. 4) are calculated. Deviations of 8 cases from simultaneous adjustment (case 1) at junction bench marks are shown in the upper row of Fig. 5. Clear deflection is seen in this result. This deflection is caused by the large closure of loop II. In such case, a method to take the mean of all cases of loop combination is proposed. Gaussian distribution of deviations of each case from this mean value is obtained, which is shown in the lower row of Fig. 5.
