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Geophysical Field Laboratory, Moore's Valley.—A special hut for magnetometer testing, observations of terrestrial magnetism, &c., constructed entirely from non-magnetic materials, has been erected at a suitable point, and is now in regular use. A second slightly larger hut has recently been erected near the upper edge of the grass clearing, and this is intended ultimately for use as a store and accommodation building. Pending the erection of the main laboratory hut and power-house, it is also acting as a temporary laboratory. A store for explosives and two equipment hutches are also installed at suitable points. A wind-charger plant has recently been installed and is being run to charge batteries and to gain some information as to its possible utility for supplying field installations in remote areas. Recordings of short-period atmospheric pressure fluctuations have been made at intervals over the past few weeks with the battery-operated microphone barograph. Air-borne Magnetometer.—This instrument is to be operated by Magnetic Survey for geophysical survey work, especially in thermal regions, after it is installed in an aircraft and operating satisfactorily in the air. After the instrument arrived from England in November it was operated satisfactorily on the ground, and is being installed in a Miles Aerovan aircraft made available by the Air Department. Time-pips Selector.—An instrument is being developed for installation at seismograph stations to enable the broadcast time signals to be automatically recorded, thus giving increased accuracy in determinations of the times and epicentres of earthquakes. Fluxgate Magnetometer Development.—Simplified equipment for measuring the strength of the earth's magnetic field on the ground, for use in field surveying and at ionosphere stations, is being developed. RADIO RESEARCH Radio-path Investigation.—Since May, 1949, this laboratory has been carrying out a continuous programme of' simultaneous measurements of absorption of radio waves reflected by the ionosphere at oblique and vertical incidence. The oblique incidence path lies between Awarua and Lower Hutt, and the vertical incidence measurements are made near Christchurch, approximately at the point of reflection of the oblique incidence radio waves. The aim of the project is to resolve a discrepancy between theory and practice which was discovered during preliminary trials, and eventually to improve the accuracy of prediction of short-wave conditions over short paths (less than 2,000 miles) in the New Zealand area. Analysis of results has confirmed the existence of the discrepancy, the magnitude of which appears to vary throughout the day. Medium-frequency Ground Conductivity Survey.—This project constitutes a survey of the electrical conductivities of New Zealand soils over the frequency range 100-1,500 Kc./s., and has been undertaken at the instigation of the Radio Research Committee. (Radio waves decrease in strength more rapidly when travelling over low-conductivity soils than when travelling over high-conductivity soils.) "When completed, this survey will enable reliable estimates of the coverage of projected broadcasting and radio navigational-aid transmitters to be made in advance. The survey of the southern portion of the North Island is completed, and it is hoped that the whole of New Zealand will be covered within the next three years.

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