density and readability, and that the cameras were running at the proper speed at zero time. . As a general rule we would need more than one dry run to prove out —the operation of a station. \ ‘However, the Parry station has been running — throughoutOperation Hardtack, and is already proved out; it will only be necessary to verify operation for the satisfaction of the U. N. Observers. 18. Equipment Protection Two natural hazards must be considered in designing a camera station such as that established at Parry? these are rain and corrosion. The dis- tance from the detonation is great enough that no problems are expected from shock, thermal radiation, or from nuclear radiations. The climate in the Marshall Islands is humid at all times, and heavy rain squalls of short duration may occur at any time. Further hazards arise from the corrosive action of sait-laden air, and from living fungus organisms. The remedies for these activities can only be preventive, and lie in the proper choice of materials resistant to them, and of shelters capable of withstanding the driving rain. The photographic equipment is housed within a cab at the top of a 300-ft tower on Parry Island. Each camera is placed on tilting/locking table, which is supported on a vertical shaft. The arrangement, which is shown in Figure 9, is similar to that employed on drill presses. By this means it is a simple matter to swing cameras in any direction for aiming purposes, to tilt them as required, and finally to lock them in position. Two such columns will be employed, each carrying three Eastman cameras. The electrical accessory equipment will be mounted in standard relay racks; each unit employing high voltages is sealed tightly to keep moisture out. Power for the cameras is obtained from a bank of storage batteries placed in the cab; power for the accessories comes from the! Parry Island a-c distribution system. " The roof of the cab has been made water-tight by applying pitch as required. The northern wall of the cab is a roller door, similar to those used on garages; the door is normally closed, and is opened by means of an electric motor when the -1 minute signal is received. matically after the last camera runs out of film. - 26 - 4 It is closed auto-