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Another point of view from which meteorology is most 
important in its bearings on the material prosperity of India 
is the effect which it exercises over the sanitary condition of 
the people. There can be little doubt that public health is 
greatly affected by the rainfall, and that fluctuations or extra- 
ordinary departures from the normal state are attended by 
fluctuations in the standard of public health. The diffusion 
and activity of epidemics are probably influenced by it. It 
would be saying too much, perhaps, to assert that the fluctua- 
tions in the death-rate are altogether due to variations in the 
rainfall, but that they are to a great extent influenced by it 
seems to be proved by what obtains all over India. 
The following* appears to have been ascertained in relation 
of climate to epidemics : — 
1. If epidemic cholera be about, its intensity will be increased 
by continued dryness, evaporation, and high temperature. If 
cholera exists under this form, heavy rain will greatly diminish 
it, or wash it away. 
2. Dryness, heat, and rapid evaporation reduce the intensity 
of fevers. Rain following, greatly increases their intensity. 
But the effect is not what can be called immediate. The rain 
must accumulate and the ground be soaked ; as soon as drying 
up begins, fever augments until the evaporation reaches a 
certain intensity, when it declines. It is not so much the 
great amount of rain as the soaking and saturation that does 
the mischief. In some places fever declines very much when 
the country is completely flooded, but increases in intensity 
when the rain ceases, and drying up begins. 
3. Small-pox in India does not appear to be related to rain- 
fall. It augments with increase of heat, and so continues till 
colder weather arrives, irrespective of the amount of rain. 
4. Rain with cold and high temperature range appears to 
augment the liability to bowel diseases, but not to a very 
great degree. 
There is yet one point to which I would refer, though I can 
only do so very briefly ; it is the influence of the rainfall on 
the growth of forests, and their effects on climate. There is 
reason for believing that some of the desert plains of India 
were at one time covered with trees, and that when they were 
so the climate was less rigorous in its extreme heat than it 
now is. When we think that the desert regions in the north- 
west were at one period the seat of early Hindoo civilization 
and population, it is obvious that the physical conditions of 
the country must have been very different to what they are 
now, and it seems probable that the change is due to destruc- 
* Dr. Sutherland. 
