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decrease in the notifications in Poplar and Bromley upon the first
rainfall.
The sewers of the Metropolis generally would not be well flushed
until the last week in July, when there was a heavy down fall of rain,
and then the diphtheria notifications for the Metropolis are seen to
have dropped.
There was a rise in the notifications in the third week of August,
both in the Metropolis and in Poplar and Bromley, and I think this
may be due to the large amount of rainfall in the preceding three weeks
saturating the earth and displacing the ground air, the barometer
also falling would cause the ground air to rise. Professor Wynter
Blyth has stated that:- "A fall of an inch in the barometer will cause
the abstraction of 57 cubic inches of the ground air, and a difference
of temperature 1 F. from the same amount of space, either an
inflow or an outflow of three and a half cubic inches."
The two last weeks of August were dry, and in September hardly
an inch of rain fell, the difference from average of 80 years of rainfall
in September was -1.39 inch; the month of September was
excessively hot, on the 24th September the maximum temperature
for the day, 87.3° F. was the highest recorded during the year, and
it was also higher than any temperature recorded at that time during
the period 1841-94.
Diphtheria notifications during the month of September for the
Metropolis ran up, but they did not do so in Poplar and Bromley.
The large amount of sunshine and the excessive heat would cause
the sides of the Metropolitan main sewers to become dry, but these
sewers as they pass through the Poplar district would again be flushed
on account of the collected rainfall they carried.
At the beginning of the fourth quarter of the year another meteorological
factor comes into play, viz., the temperature of the earth. It
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