49 
this realm are well known to Army and Navy medical officers 
as those which are most inimical to our soldiers and our 
sailors on foreign service. Here, season exercises a very 
definite influence upon their rate of prevalence and upon their 
severity. But throughout the whole of this zone the phe- 
nomena of diseases present variations, as do those of physical 
and organic nature. Certain forms of disease have within 
it their special limits. One form, namely, cholera, appears 
in this respect exceptional. Only within very recent years 
has it ever passed the limits within which for centuries it 
had been, as it were, confined ; within our own day has it 
assumed the character of a raging pestilence, sweeping over 
all latitudes, its track everywhere marked by households 
rendered desolate. 
31. The temperate zone extends from the preceding north 
and southward to the annual isothermal line of 50 deg. F. 
In the southern hemisphere, the most healthy regions in the 
world are comprised within this zone. In the northern, 
while the greatest degree of variety exists in regard to the 
processes and types of diseases, they are, as a rule, more 
manageable, less intense, and less fatal than corresponding 
attacks in the tropics. As, on the one hand, the arctic, on 
the other the tropical region is approached, so extremes and 
intensity of climatic conditions vary, so differences recur in 
the types and forms of organic nature, and so the phenomena 
of disease change, partaking more and more of distinctive 
characters, which pertain to the boundary regions. The 
British Isles lie within this zone. In them, as elsewhere, the 
death-rate of the human population is in a ratio correspond- 
ing with the extremes of temperature, between the summer 
maximum in July and winter minimum in January.* Inas- 
much, therefore, as that range is less in Scotland, the colder, 
than in England, the milder country, so is the death-rate 
smaller in the former than in the latter. With the colder 
climate also came those physical characteristics by which 
:c the children of the mist,” the brave mountaineer of 
“ Caledonia, stern and wild,” was distinguished. Shall I say, 
a difference exists as regards the diseases by which British and African 
troops in the West Indies respectively die. Thus, there died in 
1879 by Fevers 3 whites no blacks. 
„ „ Tubercle 1 „ 4 „ 
6 „ 
no „ 
2 „ 
4 
These besides injuries. Strength for the year, 1,070 white, 1,138 black. 
* Handy-Book of Meteorology. A. Buchan, p. 176. 
VOL. XVII. e 
„ Circulation no 
„ Nervous 2 
„ Respiratory 1 
„ Digestive 2 
