THE study of the upper wind currents over Mauritius with the aid of pilot balloons was begun in July 1925, and the results obtained in the early years have been discussed by Walter and McCurdy (Geophysical Memoir No. 39 of the British Meteorological Office and Miscellaneous Publications of the Royal Alfred Observatory, No. 9 are two of the papers dealing with this subject). In Part 1 of the memoir under review is summarised all the ascents from July 1928 until December 1929 in tables giving the speed and direction of the wind mostly for steps of 500 or 1,000 metres height; and also, in the form of monthly means and frequencies, the results of recent and earlier ascents. As many as 28 ascents have reached a height of 8,000 metres and 80 a height of 6,000 metres; the general summary is taken up to 8,000 metres.