28
stable of the Somersetshire lines in 1884-85, although the most exposed of four, lost none
of its occupants, while the mules were dying rapidly in all the other three (it oertainly
contained a large proportion of the small mules and none of the first class); that ponies
in Rangoon town and cantonment, which could hardly have all escaped the " wave,"
have not appreciably succumbed; and that simultaneously at places so far apart as
Rangoon and Tongnoo the disease has been raging. The balance of evidence is against
the wave theory and the influence of air. In 1883 at Rangoon, certainly, during the main
prevalence of disease at the depôt, a north-east wind prevailed, to the effects of which
the animals would have been exposed had they been in their lines, and to which many
of them were actually for a time exposed on the east glacis of the pagoda, but in 1884
it was only after the main fatality had occurred that the wind veered round to the
east; hitherto the Somersetshire lines had been rather out of the wind, which was
mainly from the south-west, so that they lay to leeward of the pagoda hill. If we
judge by the number of admissions instead of fatalities, the evidence of wind as a
determining cause is even less marked. At Tonghoo the fatalities occurred mainly
when the wind was from the west. Here also the disease seems to have prevailed
when the wind was low; evidence from Rangoon tends also to associate high winds
with less fatality. Thus sultry weather, with a stagnant state of the air, seems rather
to favor development of the disease. At Tonghoo the lines are low-lying, and mist
hangs over them after it has cleared away from the greater part of the remainder of
the station. When I was there in December it persisted until after 8 o'clock in the
morning. The outbreak in the Somersetshire lines affords us a good illustration of
a local centre. Thus, out of 55 of the cases, 23 were from A troop (3/7); 17 were
from B troop (2/7); 14 from C troop (1/4); and only 1 from D troop (1/55). The
predominance in A troop and the practical absence of the disease in D troop seems a
significant fact worthy of further investigation. "We must first examine the physical
geography and geology of the locality to see what special information can be derived
from them. The Somersetshire mule lines are situated to E.N.E. of the elevated plateau
on which the Shwe-dagon pagoda and the European Infantry lines are built. The plateau
attains a very considerable height above the sea level and above that of the alluvial
deposit on which Rangoon town and suburbs are situated, and which is continued
to east and west of the plateau as rice land, but little above the sea level. The
plateau terminates abruptly to north and east, but here and there outcrops of its
component laterite form sub-plateaux and small hills projecting from the neighbouring
alluvium. On these outcropping
prominences are situated the mule
lines, which consist in all of four
stables, named after the troops which
occupy them. A path to them has
been formed along a natural drain-
age channel. To the right of this
path are A and B stables, the latter
on a projecting spur below the level
of the former and between it the
native drivers latrine. C stable is
to the left on the highest part of the
sub-plateau. The path after a saddle
back course terminates at a pro-
minence on which D stable stands
almost at right angles as regards
its direction with the other three
stables. It is practically surround-
ed by low-lying and marsh land and
is always kept fresh and pure (if at
times somewhat cold)by its exposure
to all currents of air. Although freely exposed to all the vapours arising from the neigh-
bouring marsh land and to driving mist and fog, this stable could never become the seat
of stagnation of air ; perhaps this was the cause of immunity of animals kept in it.
Something may be attributed to good natural drainage and to the mules being of the
small thick-set stamp and to the non-commissioned officer of the troop being a specially