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can be more definite than this statement. Is it true?
How is it proved? It may be tried by three tests: 1st.
Physical examination of the properties of the air near
the water and at a distance; 2nd. Statistical analysis
of the sickness and causes of death on, near, and at a
distance from the river; 3rd. Direct medical observation.
1. Physical examination of the air near, and at a
distance from the river. I am not aware that any chemist
or meteorologist pretends to have detected or identified
the impurities which are assumed to be carried with the
vapour from the Thames, at any considerable distance
from the river. But the presence of the vapour itself,
which is said to be the vehicle of those impurities, may
be determined by the use of hygrometric instruments.
The Weekly Register of Sickness drawn up by the
Metropolitan Officers of Health, gives hygrometric
observations of the air, made day by day in different
parts of the metropolis. On searching this, I find that
during the hottest week, that ending on the 19th June
last, the mean dew-point temperature at Saint Thomas's
Hospital, which is close to the river, was 60°.2, that the
difference between this and the mean air temperature
was 9°.1; and the degree of humidity of the air (saturation
being represented by 100) was 68.6. Now taking
Hackney, a station remote from the river, I find the
difference between the dew-point temperature and the
mean air temperature was 11°.5, or greater by 2°.4 than
at St. Thomas's Hospital, and the degree of humidity