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11
subsoil air derived from soil polluted by constant infiltration
of excremental matter through a leaky drain—the
ou er margin of the infiltrated area becoming sufficiently
dry to give off micro-organisms to the subsoil air, which
then may gain access to dwellings, either through the
pressure of the wind on the surface of the ground, or
from currents induced by wide differences between the
exterior and interior temperatures.
2. Sewage does not form a medium in which much, if any,
growth of the typhoid fever bacilli takes place under
natural conditions, and the death of these bacilli takes
place in a few days, or in, at most, one or two weeks —
the interval allowing, however, of the disease being
transferred from place to place by sewage. The air of
sewers is extremely unlikely to convey typhoid fever.
Joseph Priestley.
Xonbon Counts Council.
VENTILATION OF SEWERS.
Report by Engineer as to the Result ok a Conference
of Engineers and Surveyors of the
several Vestries and District Boards of the
Metropolis.
To the Mail Drainage Committee—
In accordance with the instructions of the Committee I
issued two circular letters to the Engineers and Surveyors
of the various Vestries and District Boards in the County,
inviting them to a Conference on the subject of the Ventilation
of Sewers, with a view to some uniform system being