experiments should be constructed when the actual requirements have been deter- mined. The design of these facilities will be determined by the scientific re- quirements. Zero Towers. In line with the design requirements calling for towers to be 250 or 300 feet high and capable of fulfilling the functions connected with the experiments, as listed in the specifications furnished by Mr. R. W. Henderson dated 9-2-8, complete analysis of various types of tower structures was made. This analysis included free standing four-leg tyne towers with various base dimensions and also with counterbalancing messenger cable guys. Three- leg type guyed towers with constant triangular section above the 25-foot level and with guys affixed 50 feet below the top were investigated for above-listed heights. From the preliminary design, it was determined that the three-leg triangular type guyed tower showed approximately 35% saving in weight over corresponding four-leg towers. Recommendation is made, therefore, to utilize this triangular type tower due to lower initial cost, ease of erection and installation of appurtenances. The general appearance of the recommended tower is shown on Plate 18. The design requirements governing the above analysis are briefly to develop a tower that will support loads of 10,000 lbs. on main hoist with 2,000 lbs. on elevator alongside, minimize the weight requirement of structure in the upper 100 feet of tower, withstand the pull of two parallel catenary messenger cables with their coaxial cables, support the necessary load of equipment and personnel in the house at top of tower, and to be capable of withstanding the wind loading based on conditions to be expected in the Marshall Islands. Generally the locations of proposed Zero Towers were assumed on existing IV - 37