TBAMSACTIONS OF BECTION E. 839 



8. The Distribution of Disease in Africa. 

 Bij R. W. Felkin, M.D., F.B.S.E., ^e. 



There are not many maps existent which show at a glance the distribution of 

 •disease in any country. An attempt is made in the map shown by the author to 

 illustrate the grouping of the principal diseases occurring in Africa, so that not 

 only the existence of the disease may be seen, but its comparative prevalence or 

 eeverity appreciated. This is done by using a symbol for each disease dealt with, 

 which appears at those districts where the disease exists. The symbol is doubled 

 if- the disease is very ' prevalent, and in cases where it is exceedingly severe three 

 symbols are placed together. The climatology of various areas has also been 

 introduced, and if this map is referred to one showing the altitude, it is compara- 

 tively easy to see why dift'erent diseases should be present or absent in any given 

 region. 



On looking at the map it can at once be noted that there are three distinct 

 areas in Africa in which the distribution of malaria is widely different. It is most in* 

 tense at the coastal regions and the long banks of the great rivers, it decreases with 

 altitude and, as will be noticed, it does not obtain at all after a certain altitude, 

 over 3,500 feet. It is not found in the Sahara, as will be at once seen, except in 

 isolated areas ; again, in the extreme south of the continent it is at once apparent 

 how altitude and climatology limit its production. 



The distribution of phthisis is also seen at a^lance to be limited in its incidence 

 by altitude and climatology, and probably also to a certain extent by malaria, for 

 where malaria is most severe phthisis hardly if ever occurs. Again we notice that 

 •diarrhoea and dysentery are most frequent in those places where malaria is chiefly 

 met with, showing generally that the climatological factors producing the one 

 disease markedly influence the incidence of the others. 



It is impossible to give briefly further details with regard to the paper in any 

 other way than in tabular form. In the table, p. 838, where one* appears the 

 disease is present, where two appear it is very prevalent, and where there are 

 three it is exceedingly severe. 



9. Middle Egypt from Ptolemaic Maps and Recent Surveys. 

 By Cope Whitehouse, M.A., F.B.A.S. 



The question whether the maps which accompany the text of CI. Ptolemy, 

 A.D. 150, were copied from originals extant in the eleventh century, or were 

 draughted by the copyists of the manuscripts, by plotting the positions given in 

 the text, is of great importance. If there were original maps, contemporary with 

 the Alexandrian geographer, or not later than the fifth century, then these copies 

 furnish independent and trustworthy information as to those facts stated on them 

 which are not found in Ptolemy's lists of positions. This view has been maintained 

 by the author of this paper since 1882. 



The map of Middle Egypt, 1892, by the Ministry of Public Works, Cairo, and 

 the line of levels given by Slajor Brown, ' The Fayoum and Lake Moeris ' (1892), 

 run under his direction by Messrs. Joseph and Pini, furnish a crucial test. The 

 section of fifty-two miles from Beni-Suef to the furthest trace of habitation in the 

 N.W. Fayoum is nowhere above the level of the Nile, except in crossing the 

 promontory of Dimeh — the island-pyramid in Moeris of Herodotus and Diodorus. 

 It would be an island if the water in the Fayoum stood at the level of + 6 metres ; 

 high Nile being taken at about + 30, and the present Birket el-Korun at — 48 

 metres. 



Noting the successive changes through which this region passed, as shown by 

 its physical conditions, history, and archaeological remains, it may be established 

 ■with certainty that the positions of the places mentioned by CI. Ptolemy could not 

 have been plotted on a map of the middle ages, nor on a map of ancient Egypt, 

 reconstructed from the historical and geographical data of Herodotus (b.c. 454), 

 Diodorus (B.C. 20), of Strabo (b.c. 24). Such attempted reconstructions by Linant 

 and others were shown ; and the differences between them and Ptolemaic maps 



