A.-4

The seismological data for the year ending 31st December have been published, and reports sent to about eighty seismic stations. At the request of Science Service, radio reports of all large earthquakes occurring in the South Pacific are sent at its expense to the United States Coast and Geodetic Survey, Washington, D.C. Meteorology. There are five main divisions in the meteorological work : (1) Routine observations at Apia ; (2) upper-air investigations with pilot balloons ; (3) atmospheric electricity ; (4) solar radiation ; and (5) supervision of weather stations in Samoa and other islands. Routine Observations at Apia. At the Observatory continuous records were obtained of temperature, barometric pressure, rainfall, humidity, and sunshine. A resume of these data is here given :• —

A cyclone passed through the Samoan Group on the Ist January, 1926. The barometer at Apia fell to 29-14 in., and the wind in gusts had a velocity exceeding seventy-five miles an hour. The cyclone originated near the Union Islands within 8° of the Equator, and at the latitude of Apia was about 300 miles in diameter with a calm area in the centre of about 10 to 15 miles. The whole disturbance moved south-south-east at the rate of fifteen miles per hour. On the 31st March a second cyclone centre passed close to Upolu with approximately the same path as that of the Ist January. Fortunately the wind-gusts were not so violent at Apia in the March cyclone, although earlier in the Union Group, and later on in the Cook Group, the storm was much more destructive. The damage to vegetation caused by the January cyclone was increased by the unusual dry weather and bright sunshine which occurred during the following month. The annual rainfall was 103-57 in.—3-28 in. below the normal, largely through deficiencies in January, February, and May. The mean temperature was 79-76° F.—l-28° F. above normalindicating that the slow increase in temperature since 1890 is still in progress. A Dines anemometer, which has been needed for some time, was ordered in June, 1926. The 1924 annual report was received from the printers in the last quarter of 1926. Owing to unavoidable delays in publishing statistics, a monthly meteorological report is cyclostyled and sent to eighty institutions and investigators. Upper-air Investigation. A total of eighty-three small rubber balloons inflated with hydrogen were sent up during the year ; thirty-four of these were observed to heights greater than 10 km., and one to an extreme altitude of 28-0 km. (17 miles). The observations have shown that the trade winds on an average reach 5-5 km. (3-4 miles), a height somewhat greater than had at first been believed. Above the trade-winds are the eastward-moving antitrades, which seem to have their maximum velocity about 11 km. (6-7 miles). At the request of the Australian Air Force a resume of the data obtained in regard to winds during the past three years was prepared for their guidance in the proposed flight to Samoa in November, 1926. Atmospheric Electricity. The measurement of the electrical potential of the atmosphere has been continued throughout 1926 at both the station in the Observatory grounds and at the station erected above the waters of the lagoon about half a mile from shore. These stations, giving simultaneous records, not only afford a useful check on each other, but provide data on the effects produced by a unique maritime exposure. An article giving the results already obtained was published in the Journal of Terrestrial Magnetism, September, 1926.

34

Temperature Extremes. Barometer . Month of 1926. j Mean Sunshine. Humidity. Rainfall. High. Low. Values " °F. °F. Inches. Hours. Per Cent. Inches. January . . . . .. 905 71-1 29-76 1954 83-1 10-94 February .. .. .. 89-2 75-0 29-75 129-3 84-8 9-85 March .. .. .. 85-2 75-9 29-79 138-1 87-5 15-79 April .. .. .. 88-2 69-8 29-86 173-9 83-1 5-30 May .. .. .. 88-5 70-9 29-87 255-7 83-6 1-24 June .. .. .. 89-4 67-3 29-90 222-2 81-9 5-84 July .. .. .. 87-4 67-5 29-89 247-6 82-4 4-55 August .. .. .. 88-3 70-2 29-93 240-7 80-4 3-80 September .. .. .. 87-6 71-3 29-91 234-9 82-0 3-32 October .. .. .. 88-0 66-2 29-86 260-7 83-2 6-87 November .. .. .. 87-8 72-3 29-82 176-6 86-0 14-20 December .. .. .. 88-5 72-5 29-82 174-7 85-6 21-87 Totals and Means .. 88-22 70-83 29-847 2449-8 83-63 103-57