CHAPTER 5,12 SCIENTIFIC STATIONS The Engineering Division of Holmes & Narver prepared designs and drawings for many Scientific Stations from sketches or outline specifications furnished by the various scientific groups participating in the experiments for Operation Greenhouse, This phase of the work of the A-E-C-M Contractor grew steadily as additional scientific groups were included in the experimental program and as the requirements of others were increased in scope, Many changes were requested late in the program, and the Engineering Division of Holmes & Narver was under pressure to prepare plans and requisition materials to meet requirements on time, To provide for anticipated changes or additions desired by the Users, certainmaterials were stockpiled at the Jobsite. Accurate records of these stockpiles were kept in the Engineering Division office in order that designs might be made to utilize these materials and thus save considerable time. Other materials were requisitioned from draw- ings as soon as they were prepared and before the Users had reviewed them or from sketches supplied by Users, In this manner, loss of time in waiting for special materials was minimized, Drawings were revised to include changes required by Users and then forwarded to the field. If the structure was already under construction, changes were teletyped to the Jobsite and drawings were revised and sent later. Most of the scientific structures were designed to resist blast pressures, the magnitude of blast-resistance being established by J-Division of the Los Alamos Scientific Laboratory. These blast-resistance requirements underwent a considerable number of changes as the program developed, and these changes involved a great deal of back checking of designs to evaluate the effects of modifications to structures, The pressures for which various structures were designed are recorded in code designations on the drawings, and the apparent structural performances of the structures during the experiments are recorded in Chapter 5.27 of this volume, CIVIL ENGINEERING FOR SCIENTIFIC STATIONS In accordance with recommendations in the Reconnaissance report of January 7, 1949, the new zero tower position on each of the three experiment islands was located on the old zero line extended 75 feet northwesterly from the old Sandstone zero point. The new zero loca- tion on each experiment island is the focal point from which all scientific structures are oriented by azimuth and distance, The azimuth of the zero line as shown on the maps of Joint Task Force Seven is used as the base of bearings on each experiment island, On the plans for scientific and special structures prepared by Holmes & Narver, the azimuth shown reads from the scientific structures look- ing toward zero, measured in degrees of angle clockwise from due north. 9 155