ii
8. The effects of
configuration of the
surface on move-
ments of air cur-
rents, and on venti-
lation ?
Dr. Fitzgerald, a Medical Officer who has practically studied this
question during a long residence at the station, has recorded as
follows :—
" Palaveram occupies a very favourable position on the sanitary scale,
and I believe that on the cholera map it appears without a stain.
There have been cases of that disease in the station (and the past
year 1860 afforded several), but they were instances of persons who
had come from other places where it was raging epidemically, or
else of men whose constitutions were broken down by habitual
intemperance, or other causes.
" The position of the cantonment relatively to the adjoining hills has been
looked upon, and often spoken of as faulty, inasmuch as they are
supposed to intercept the sea-breeze, and to add considerably to the
heat by radiation and reflection.
" Since I came to reside in this station I have paid considerable attention
to this subject. I think that the general salubrity of Palaveram and its
immunity from epidemic cholera are due, in a great measure, if not
altogether, to its so-called faulty position.
" Owing to their conical form and the funnel-shaped gorge between
them, the Palaveram hills do not intercept the sea-breeze, except from
very limited spaces close to their base ; but they divide it into different
currents, which rush round their flanks and through the gorge
already mentioned with accumulated force, and sweep through the
cantonment in various directions.
" In its present position, moreover, the cantonment is open to the free
play of the north-east and south-west winds, whereas had it been
placed on the other side of the hills, there would have been nothing
to prevent a Native town and bazaar springing up to seaward.
" There is another effect produced by isolated hills of moderate eleva-
tion, like those at Palaveram, which does not appear to be taken into
account in connexion with this subject as much as it deserves. I
mean their influence on the movement of the atmosphere. When
this is perfectly still and motionless near the surface of the earth,
there is usually, at the same time, a steady, though gentle, movement
in its higher strata, and when the peak of a conical hill rises up through
these, the obstruction it occasions gives rise to a number of broken
currents of air around it, whose movement is communicated to the
lower strata, and prevents that stagnation which often occurs on low
level plains remote from hills. The effect also on the temperature
of the higher strata of the atmosphere of masses of rocky hills pene-
trating them, tend to promote that movement and agitation of the
surrounding air which is so salutary in such a climate as this. I
have repeatedly verified for myself this influence of the Palaveram
hills in producing currents of air in their immediate vicinity, when
at a short distance, not the slightest movement was perceptible."
Having myself lived on the top of one of the hills for some weeks, ascend-
ing and descending daily, I can fully confirm Dr. Fitzgerald's remarks
on the effect of the configuration of the hills upon the aerial currents
which sweep over the cantonment.
9. Country open,
or encumbered with
vegetation.
Open. Scanty vegetation.