268 Proceedings of Royal Society of Edinburgh. [sess. 
With regard to the data concerning the geographical distribution 
of the diseases, I am indebted for my principal facts to the Hand- 
book of Geographical and Historical Pathology , by Dr August 
Hirsch, and to the copious bibliography which accompanies his 
various chapters. I have not, however, hesitated in any case where 
my own information, or information gathered from other sources, 
modifies or supplements his data, to make use of the same, and I 
have as far as possible verified the facts I have given. 
The maps which illustrate this paper have been specially prepared 
for it, and in order to ensure as great accuracy as is possible on such 
small maps, the areas of the distribution of the various diseases have 
been drawn upon large maps used for lecturing purposes, and sub- 
sequently reduced by photography to the scale suited for publication 
in the Proceedings of this Society. 
The maps illustrating some of the physical phenomena with which 
my paper deals are adapted from various sources. The chart of the 
world depicting the mean annual temperature of the tropical and 
sub-tropical zones is taken from the Challenger Reports , and is based 
upon the most recent investigations on the subject. The chart 
representing the mean annual rainfall throughout the world is after 
the most recent map published, namely, that in the Contributions to 
Meteorology , by Professor Elias Loomis (1889). 
Plate No. 16 gives the isoclinal lines with reference to pandemic 
waves of disease, and the prevailing winds upon the ocean. It has 
been compiled from two maps; one published by Dr Robert Lawson 
in 1888, and the other by Dr W. S. Wilson in 1881. 
I trust that this paper may be of special interest to members of 
my own profession, who will be able to see at a glance the diseases 
infesting the various districts in the tropics, and who will therefore 
be the more readily able to give the necessary advice to patients. It 
should be useful to intending emigrants, and of special service to 
insurance companies, as indicating the areas of comparative safety or 
risk for the residence of their clients. 
The diseases treated of are — 1. Malaria; 2. Dengue; 3. Asiatic 
Cholera; 4. Yellow Fever; 5. Oriental Boil ; 6. Endemic Hsema- 
turia; 7. Beri-beri; 8. Oriental Plague; 9. Dysentery; 10. Leprosy 
(Elephantiasis Grecorum); 11. Yaws; 12. Fungus Disease of India; 
13. Elephantiasis Arabum (Barbadoes Leg); 14. Guinea-Worm; 
