in these mixes than in coral concrete mixes, no adverse thermal cracking was noted. A limonite concrete mix was designed to produce a unit weight of 312 lbs. per cu. ft. for a small margin in excess of design requirements without increasing mixing and placing difficulties. Compressive strenghts in excess of 3000 psi were realized from these dense mixes but the amount of mixing water had to be sharply restricted in order to produce the required unit weights. Compressive strength and unit weights obtained on the limonite concrete were good. The results of all the limonite concrete test -cylinders show that an average compressive strength of 3259 psi was obtained at 28 days, The in-place unit weights of limonite concrete structures were checked by carefully calculating the capacity of the forms and comparing the volume with the number and weights of all batches of concrete going into a particular pour, Very close or exact agreements were obtained between the unit weight of the mix design and the calculated in-place unit weight. Figure 24 shows monthly totals of all concrete poured. Testing of the submarine cables remaining from the IVY Operation re- vealed that cables from Engebi to Bogallua were not intact. However, suffi- cient usable cable remained to meet the CASTLE requirement for termina- tion at Bogon. The cable serving Bogallua and Bogombogo required replacements and repairs. Approximately 45,000 ft. of new six-pair and 10,000 ft. of new 16-pair telephone cable were required to serve the scientific stations. Despite the fact that firm criteria were not available when cable procurement was initiated, plus subsequent changes in the scientific program, the amounts of cable originally purchased for the Eniwetok Atoll system were less than ten percent in excess of final needs. Submarine cables were laid from a modified LCM type landing craft and all splices were made aboard. Testing of the cable was continuous during laying operations and terminations were made in existing submarine cable terminals at the various island sites. All cable work was completed as planned with the exception of the new six-pair telephone cable between Bogallua and Bogon. Installation of this cable was held up pending finalization of requirements, and early in April 1954, advice was received that this installation had been deleted from the program. Since an entirely new submarine cable plant was required for Bikini Atoll, it was decided that combined telephone and signal usage of a single cable system was feasible instead of a double cable system as employed at Eniwetok Atoll, This single cable system required special splice boxes which provided inductive loading coils for those cable pairs used for telephone trunking or telemetering. However, considering the amount of cable involved, combined use permitted a reduction in length of over 500,000 lin. ft., or slightly more than 50 percent in submarine cable requirements. The saving in cost of the installation was directly proportional to the reduction in length. 49