National Geographic : 1926 Jul
photograph trom Lieut. Commander F. A . Zeusler READING THE DEEP-SEA REVERSING THERMOMETER Thermometers are secured in the two parallel tubes shown with the holes at their upper ends. At the same time that the thermometers are tripped, recording temperatures, the chamber at the right-hand side of the instrument falls, securing a sample of the sea water. It is drawn off in bottles when brought on board. Photograph by Lieutenant N. G.Ricketts SETTING THE COURSE AND LATITUDE CORRECTORS The gyro compass is aninvaluable aidonice patrol, where itisabso lutely essential that the ship's position beknown at all times accurately. This instrument is very reliable when properly cared for. Itisapiece of "fancy machinery," however, comprised of wheels within wheels. This type, with the repeaters and recorder, cost $6,000.