parts of Africa which are unsuitable for European settlement (a) throughout the year, 

 (b) for eight months of the year, (c) for four months of the year, or (d) suitable for 

 more than eight months of the year. 



When a diagram such as Fig. 3 shows that four hours of the day in a particular 

 month fall to the right of the line CC, it is concluded by Jackson that the place in 

 question is unsuitable for Europeans during that particular month. The work invol- 

 ved in drawing such a map as that shown by Jackson is completely straightforward, 

 and requires only reliable values of temperature and humidity for each hour of the 24 

 in the day. His map for regions south of the Sahara is shown in figure 4. 



Dr Jackson's work is, as he himself states in the publication referred to*, only 

 a first approximation. It does not take account of winds, nor of the possible effects 

 of a long stay in a monotonous climate, which is regarded by some writers as having 

 a serious effect in leading to a loss of initiative and efficiency. 



In the brief statement above, I have endeavoured to show the vital need to make 

 use of the fact that in some parts of the globe active outdoor work is only possible 

 during some hours of the day, or during some months of the year. There is a great 

 need to collate records of the hours when work is possible with the meteorological 

 records available, and possibly to institute new meteorological stations in regions 

 as yet unprovided with records. I should regard such collation as a most useful ad- 

 dition to the knowledge we have acquired by laboratory experiments on human sub- 

 jects in controlled atmospheric conditions. 



I have asked that the African Regional Association of the World Meteorological 

 Organization should discuss this matter at their forthcoming session in January 1953, 

 with a view to considering what information they can supply. If any information can 

 be obtained by this means, or by any other means, I should be glad to do the work of 

 reducing and discussing such observations. 



* Jackson, S.P. 1951. Chapter 1 in: Africa South of the Sahara. Oxford University Press. 



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