Politically the archipelago is an independent Arab principality ruled by a dynasty 

 established towards the end of the eighteenth century. The principality is in special 

 treaty relations with the British Government, which maintains a Political Agent in Bah- 

 rain and has lately transferred there the headquarters of its Political Resident in the 

 Persian Gulf. Bahrain is the centre of a pearl - fishing industry of great age; it has an 

 important oil- field; and it is becoming an increasingly significant centre of air and 

 other transport. It is also renowned for the great numbers of sepulchral mounds or tumuli 

 which cover considerable parts of its surface and which are generally thought to be bet- 

 ween three and four thousand years old. The population is mainly concentrated in the 

 two coast towns of Manama and Muharraq and at a recent cencus amounted to about 

 120,000. 



Climate 



The Bahrain Islands have a remarkable and somewhat notorious climate in which 

 the chief characteristics are high summer temperatures; scanty and irregular rainfall; 

 high relative humidity ; and rather persistent, though rarely very violent, wind. There 

 are recording stations at Muharraq Airport and at the Bahrain Petroleum Company 

 (BAPCO) desert town of Awali, and there is probably sufficient information available 

 for a detailed study of conditions, but for the present purpose they may be illustrated 

 by the following sample figures, based, unless otherwise stated, on the year 1947. 



The mean annual temperature is about 80°F, or perhaps a little more, and the ex- 

 treme temperature variation during the year is about 70°F. Monthly figures are:- 



The average annual rainfall for ten recent years is 2.46 inches but the total var- 

 ies greatly from year to year as shown by the 1946 figure of .15 inch and that of 1940 

 which was 5.53 inches, or nearly forty times as much. Rain falls on an average of about 

 20 days a year and there is practically none between late April and November, the mon- 

 thly figures for 1947 being :- 



J. F. M. A. M. J. J. A. S. O. N. D. 

 .3 .6 .2 - .1 _ _ _ _ _ „7 .1 



The relative humidity ranges during the year from to 100% and in 1947 the aver- 

 age daily maximum was 83% and the average daily minimum was 25%. The lowest daily 

 maxima were 38% on 4 December and 54% on 3 June; the highest daily minima were 74% 

 on 19 March and 70% on 8 January and 18 February. 100% was reached on 21 occasions 

 in February, October and November (compared with 100 occasions, nearly all in the lat- 

 ter half of the year, in 1949), and the daily range varied from 4% on 19 March to 85% on 

 18 September. 



There is a fairly constant light to moderate wind apparently throughout the year 

 which comes prevailingly from the northern quarters and especially from the north-west. 

 This wind is commonly called a shamal locally and tempers the climate, while the rarer 

 southerly winds tend to be oppressive. During the first seven months of 1947 there was, 



46 



