266 
Proceedings of Royal Society of Edinburgh. [sess. 
On the Geographical Distribution of some Tropical 
Diseases, and their Relation to Physical Phenomena. 
By R. W. Felkin, M.D., F.R.G.S., Lecturer on Diseases 
of the Tropics and Climatology , Edinburgh Medical School. 
(With 16 Plates.) 
(Read July 15, 1889.) 
The subject of the present paper has occupied my attention for 
some years, but I may state that what follows is the outcome of 
notes prepared for lectures to my students and is only a pre- 
liminary attempt to focus our present knowledge of the geo- 
graphical distribution of some tropical diseases, and to indicate as 
far as possible the knowledge which we at present possess of those 
physical phenomena which influence the production of these diseases 
and the area of their distribution. Why, for instance, some diseases 
are confined to limited areas of distribution, whereas others are 
endemic in extensive districts, and others again periodically 
extend their ravages throughout clearly defined, though wide- 
spreading, regions. 
A map was published by A. Keith Johnston in 1856 representing 
the geographical distribution of health and disease, chiefly in con- 
nection with natural phenomena; but although it gives a great 
deal of information, it does not indicate with sufficient clearness 
the definite areas of the various diseases referred to. Since its 
publication, too, our knowledge both as to the distribution of 
tropical diseases and the cause of disease has made considerable 
progress. More recently Mr Alfred Haviland, M.R.C.S., pub- 
lished three very valuable and instructive maps dealing with 
the geographical distribution in England and Wales of cancer 
in females, of phthisis in females, and of heart disease. These 
maps show very strikingly the influence exerted on these diseases 
by locality. 
Two maps, illustrating the distribution of diphtheria and scarlet 
fever in England and Wales, were published by Dr E. G. Barnes in 
the British Medical Journal , July 28, 1888. In the same Journal 
for January 19, 1889, there is a report of the collective Investiga- 
tion Committee of the British Medical Association, prepared by Dr 
