Hæmotological investigations in Baghdad suggested that the climate altered the blood of normal persons as compared with Britain, and as part of the analysis of the climatic factors, day-today measurements were made of the ultra-violet component of northern sky shine, using Owens's instrument. In this a Chance No. 14 filter is separated from a sheet of photographic paper by a graded series of tubes, giving a scale of 13 arbitrary values from 1 to 204. 'The upper end of the scale is much more open than the lower, and this must be considered a disadvantage in very bright conditions such as the Iraq summer. The instrument is exposed for 24 hours at 45° to the zenith pointing north.
The daily measurements from August, 1936, to August, 1937, are given in graphic form, and also as monthly means. With the latter, various other meteorological data are tabulated to show the trend and range of climatic variation, and to indicate some of the major causes of fluctuation in the ultra-violet values. The direction of influence of these variables is discussed briefly, but integration of the factors is not attempted. The paper is preliminary; further studies are in progress.