H.—34

APIA OBSERVATORY, SAMOA. Director : J. Wadsworth, M.A. (Cantab.). The same programme of work in geophysical subjects was followed during the year 1934-35 as in the past, the principal subjects of study being terrestrial magnetism, seismology, meteorology, and atmospheric electricity. Terrestrial Magnetism. The work in terrestrial magnetism comprises absolute measurements and continuous records of the elements of the earth's field. The former were made with a Tesdorpf magnetometer and a Schulze earth inductor, while the latter were made with Eschenhagen variometers and a Godhavn balance. The results are tabulated in the form of hourly values of horizontal intensity, declination, and vertical force. The variometer for horizontal force was accidentally disturbed in July during an experiment which was carried out to test the coefficient of temperature, Till then its scale value at the base line was 147y per millimeter, but subsequently it was adjusted to be l-08y. The Godhavn balance was set up de novo in June, 1934. The north pole of its needle was set towards magnetic south-east and the resulting scale value was 1-05y per minute of arc. Its records are satisfactory, except that the trace of the spot of light from the movable mirror is very faint. The mean values of the magnetic elements during 1934 are as follows Declination . ■ ■ • . . 10° 42-2' east, from autographic records. Horizontal force . . . . ■ • 35049y, from autographic records. Inclination (or dip) . . •. . . 30° 22-f, from 27 absolute readings. Seismology. The instruments used for seismological work at Apia are the 1,000 kilogram astatic pendulum and the 80 kilogram vertical seismograph designed by Wiechert. The number of earthquakes recorded during the year ending on March 31st, 1935, was 176. About 15 of them were slight local shocks which could be felt by ordinary residents, while the majority of the remainder were insignificant tremors. The earthquakes recorded on July 18th,, 1934, were probably the disturbances which took place m Panama and the Santa Cruz Islands. The vertical seismograph is very insensitive, and latterly it has not been used. Meteorology. Meteorological work includes surface observations twice a day and some measurements of the upper winds from time to time using pilot balloons. Since January Ist, 1935, the times of the daily observations have been 9 a.m. and 3 p.m. Zone time (165 degrees west). The method used with pilot balloons has been normally the method known as the single theodolite. During the year ending on March 31st 1935 the number of pilot balloon ascents was 63 and the greatest height reached was 37,500 ft. Measurements of the duration of bright sunshine with the Fuess recorder were resumed in September, 1934, on the arrival of a new glass ball from Germany. Rainfall reports are being received from a new station at Lotofanga, on the south coast of upolu, which we owe to the good offices of the Roman Catholic Mission. The number of local rainfall stations in Samoa is now about 19. . The synoptic weather reports of the South Pacific were discussed m a meeting which took place on July 2nd, 1934, on board H.M.S. " Dunedin," at Apia. It was finally decided to use the code of Copenhagen 1929 in the form known as " weather shipping," and a regional system was recommended in which, the central stations are Suva, Apia, and Papeete. These changes came into effect on January Comman( ji rl g H.M.S. " Laburnum " kindly inspected the meteorological stations at Atafu and Fakaofo during a cruise to the Tokelau Islands in June, 1934, and took a barograph back to Atafu which had been sent to Samoa for repair.

Meteorological Summary, 1934.

15— H. 34.

107

Month. Pressure. Temperature. Rainfall. Sunshine.* Wind. Miles per j n °F In. Per Cent. Hours. Hour. January .. •■ 29-794 79-4 15-25 80 144-1 5-1 February .. ■■ 29-827 79-4 J 11-54 81 .. 3-6 March " ■■ 29-776 78-6 20-03 84 4-0 Wil .. 29-824 78-7 7-42 79 .. 3-8 ifoy .. 29-851 79-0 6-09 81 .. 4-9 June" .. 29-865 78-7 1-64 78 .. 7-5 j ulv . .. 29-859 78-3 7-74 81 .. 6-9 August •• 29-892 78-1 1-10 73 .. 9-4 September .'. \. 29-872 78-7 10-41 77 225-4 7-0 October . 29-873 78-9 4-90 75 243-6 6-9 November " .. 29-806 79-4 14-05 79 188-8 7-7 December \\ .. 29-742 __79-4_ _*>05_ __81 6-6_ Total • 120-22 Mean '.'. .. 29-832 78-88 .. 79 .. 6-1 * No readings from February to August. Glass ball lost.