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Show 354 THE NATIONAL GEOGRAPHIC MAGAZINE tered during each flight. Weather forecasts were prepared by the aerographer in so far as was practicable from the meager data available in Arctic Regions. A special study has also been made of all unusual meteorological phenomena and photographs relating to these phenomena have been obtained in many instances. All aerological observations have been carefully recorded and a journal has been written to assist in their interpretation. These data, it is hoped, will form the basis for an analytical study of Arctic conditions upon the return of the expedition. Mr. Francis has also had charge of the Navy's photographic equipment. COAST SURVEY REPRESENTATIVE STUDIES TIDES AND SOUNDINGS Lieutenant Benjamin H. Rigg, loaned to the expedition by the United States Coast and Geodetic Survey, has carried on an important series of observations of tides, currents, water temperatures, and densities. Tidal observations have been made at every point possible. At places where less than three days were spent the readings were made on a plain staff every hour, except near the times of high and low water, when readings were taken every five or ten minutes. Where a stop of three days or more was made, the readings were taken with a portable automatic tide gauge in connection with the plain staff. Wherever practicable, bench marks were established in connection with the tide staffs, so that the planes of reference determined by these observations might be recovered at future times. Whenever possible, Lieutenant Rigg established three standard bench marks. Current observations have also been made by means of a current pole about 15 feet in length, weighted with sufficient sheet lead to submerge all except one foot of it. A log line graded for 60-second run was used in connection with this pole, the 60-second interval being determined by a stop watch. In many instances it was possible to make observations with the current pole every hour, and in addition observations were made half-hourly with a Price current meter at three depths-one-fifth, one-half, and four-fifths of the depth at each station, except that the lowest observation was not made below 80 feet. In most cases the observations began at the depth nearest the surface, and in every case the exact time of the observation was recorded. Whenever practicable, temperatures and densities of the sea water have been taken twice a day-at 8 a. m. and 8 p. m. in most instances. Like the current observations, those of temperature and density have been made at three depths-one-fifth, one-half, and four-fifths of the depth of the station. These temperature observations have been made with a deep-sea thermometer in a reversible frame, and the water samples for density determination were secured with the Sigsbee specimen water bottle, the density being determined with a hydrometer in the usual way. Lieutenant Rigg's equipment included a portable automatic tide gauge, complete with 20 feet of 3-/j-inch pipe ; a plain staff 12 feet long; a stop watch; a log line, graduated for 60-second run; a Sigsbee specimen water bottle; two sets of hydrometers, a hydrometer jar, two deep-sea thermometers; a reversing frame for deep-sea thermometer; a water thermometer, and an air thermometer. It is believed that Dr. Leo M. Davidoff, the surgeon of the expedition, will have much to contribute to its achievements from a scientific standpoint. His researches have been wide, for the general good health of the personnel has left him free to study many natural history specimens collected in the Arctic. All in all, the members of the National Geographic Society may well feel gratified at the scientific data collected by the expedition which they have sponsored. |