Teletype and Mail Service. On February 2, 1958, the Task Group 7.1 Mail and Records Section for Operation Hardtack opened at Parry Island, Eniwetok. Bikini. On February 15, 1958, a branch office was opened at Enyu Island, OnJune 15, 1958, another office was opened at Johnston Island. Civilian aid military personnel were used to man the three offices. The maximum strength at Parry Island was nine; at Enyu Island it was two; and at Johnston Island it was five. The Parry Island office was open 24 hr a day, seven days a week throughout the operation, and the other two offices were open from 0700 until 2400 hr seven days a week. Teletype service was furnished at all locations for the entire Task Group and accounted for the greatest portion of the total work load. During Hardtack, the following listed teletype traffic was processed by the three offices: Classified Outgoing 1,261 Classified Incoming 3,293 Unclassified Outgoing 6,306 Unclassified Incoming 12,272 Total 23,132 The Task Group Mail and Records Section normally handled official cor- respondence only for LASL. However, service was provided for non-LASL units until these organizations had their mail system in operation. Personal mail was handled in a similar manner. A daily pouch was sent between the mail rooms at Eniwetok and Bikini Atolla. This service was available to all units of the Task Group and pro- vided an expeditious means of transmitting unclassified and classified (up to and including Secret RD) correspondence between sites. A similar service was provided between Eniwetok Atoll and Johnston Island on the weekly re- flector flight and on the MATS flight which stopped there once a week. A Task Group Reading File was maintained by the Parry Island office. This file consisted of copies of outgoing correspondence and teletypes and was circulated among the headquarters staff sections. Communications at Eniwetok ProvingGround. The Commander of TG 7.5 provided TG 7.1 with all the long and short range communications including cryptographic service. The individual projects were responsible for installation, maintenance, and operation of all scientific electronic equipment. Task Group 7.1 had approximately 13 voice nets including the EniwetokBikini-Boxer ciphony system. The primary net was the Command Net, which was used by the Staff Sections and Task Unit Commanders. In addition, each Task Unit had its own individual net. Two neta were reserved for calibration purposes and proved to be of great value. The major nets were serviced by a repeater station which was located on towers at 150-ft levels at each atoll. The installation of antennas began in early February 1958 and radio sets were installed upon the users' request after arrival in March 1958. The JTF 7 Weather Detachment provided communications to the following off-atoll scientific sites: Kusaie, Kwajalein, Rongelap, Utirik, Ujelang, and Wotho. Wake Island was serviced by the CAA at Wake. In addition, the respective off-atoll projects provided their own communications links between their respective sites. Drill messages were sent in April 1958 to provide training to all off-atoll sites. A radio silence requirement during all shot times was establighed by 1038