Stations 40 - Engebi, 41 - Muzin, 42 — Runit — J-7, LASL. The sketches for these stations were given to H&N on May 6, 1950, Stations consisted of a reinforced concrete well 5 feet, 2 inches, by 3 feet, by 3 feet, 6 inches deep capped with a 1/2 inch plate cover, Over the well was a rack 7 feet high and 7 feet wide made of 2 inch standard pipe. The electrical lines entered the well via a 2 inch conduit 10 feet long that was buried a foot beneath a 3 inch macadam surfacing, The surfacing covered an area 25 feet by 30 feet. The front of the well had a lead shield 12 inches thick which was also extended one foot along the side walls, Originally Station 42 was located on The Aomon Group, but it was moved to Runit on October 4, 1950, It was relocated on Runit on October 26, 1950, in order to clear the camp area, Stations 50a, b, c, d, and e - Runit, The Aomon Group, and Engebi ~- NBS. As these stations measured radiation, the use of lead and limonite concrete was necessary, These stations had a limonite pad 8 feet, 6 inches by 8 feet by 1 foot, 4 inches thick, the top of which was flush with the ground level, Through the center of this pad was a 6 inch diameter hole with a 4 inch thick lead shield around the hole, Under the pad was a well with inside dimensions of 2 feet, 6 inches by 2 feet, by 1 foot, 8 inches deep. The well had plain concrete walls 12 inches thick. A center section of the pad 2 feet, 10 inches by 3 feet, 4 inches could be lifted out to give access to the well. Immediately adjacent was a redwood battery box 5 feet by 2 feet by 3 feet deep, Station 50a had two wells under the pad; therefore the pad was & feetby 11 feet in area, The original sketches were furnished on February 8, 1950. The necessary tolerances were given March 3, 1950, The battery boxes were added July 1, 1950, and NBS approved the drawings on July 18, 1950, Stations 50b, c, and d, Engebi and 50d, The Aomon Group, were relocated on August 4, 1950. Stations 50b, c, and d, Runit, and 50d, The Aomon Group, were relocated on September 6, 1950, Stations 51a, b, c, and d — Runit, The Aomon Group, and Engebi — NBS. Essentially the same as Station 50, except that no lead collar is needed, The sketches for these were furnished June 1, 1950, On June 14, 1950, J-Division requested work stop until new sketches were forwarded by NBS. These were received on June 28, 1950. The battery boxes were added on July 1, 1950, and NBS approved the drawings on July 18, 1951. Stations 52 and 53 - Runit and Engebi - NBS. On March 3, 1950 request was made for designs to be prepared for NBS Stations 52 and 53 based upon outline sketches of the requirements as prepared by the User. The essential requirement of the structureswas to provide a unit which would support a considerable number of collimator tubes all alligned at different angles with the horizontal plane and protected with a minimm amount of limonite concrete shielding, all as established by the User, It was also required that information could be salvaged from these units after the test, 5-163