the original azimuth observations were made from station North Base to station South Base, an examination of the corrections obtained for the angle in the U. S. S. BOWDITCH triangulations showed that little accuracy would be lost by accepting the azimuth of the line from station North Base to station Sand as the basis of azimuths for the survey. Therefore it was considered that the cost of re-observation for azimuth was not justified. The line North Base-Runit was measured to first order accuracy, and the azimuth of the line was computed from its relation to the line North Base-Sand, The computations involved in establishing the azimuth of this new base line have been checked and are included in the horizontal control report for reference purposes. A copy of the Report of the Engineer, Joint Task Force Seven, Part 2, was made available and was of great assistance in planning and executing this survey. After completion of this primary network, additional Project requirements resulted in expanding the system to include stations on six additional islands, Muzin, Kirinian, Eberiru, Aaraanbiru, Bogon, Rigili, and location "M" on the reef south of Runit. Although except for Eberiru, Aaraanbiru, and Rigili these local systems do not meet all standards for second order work, particularly in strength of figure (because of limited area and values arrived at in adjustment), it is felt that the errors in the linear distances from those computed positions to any other point in the triangulation system will not exceed that allowed for second order work. (See Figure 5.8-4 for the supple- mental triangulation net. ) The determination of positions on Eberiru and Aaraanbiru was necessarily made by poorly shaped triangles, but one side of every triangle used was precisely measured to first order accuracy, and computed lergths of common sides were in very close agreement. It is therefore felt that these determinations will exceed those normally obtained by second order work. Rigili was located to third order accuracy because request for determination of a station on the island came quite late in the Project; because the island was to be used for only one camera station, results of which would be affected by the difference between a second or third order fix of position; and because, owing to the curvature of the earth, the only possible means of observation was by eccentric lights mounted in the cabs of the zero towers at Engebi and Runit and a light on top of 100' tower (now dismantled) over triangulation station Parry. Results obtained in occupying these towers with instruments were not very satisfactory and were used as a check in adjusting the position arrived at by using the two angles at Rigili, measured between the three lights mentioned above. The completed network consisted of twenty-three stations, including five stations of the Joint Task Force Seven Survey, two of which were 5-61