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on occasions bait was placed outside the traps, the birds did not, and
apparently will not, feed near the roosting places.
During the course of the observations, it was found bhat birds roosted
less frequently on buildings that were painted externally, or which had
a glazed surface on the copings and ledges. Recently small portions of
one of the ledges on the City Hall on which starlings normally roost,
have been treated with different types of paint. Observabion over a
considerable period will be required before the results of this experiment
can be assessed.

The type of noise of which complaint has been made varies
considerably and has included noise created by machinery of several
kinds, electric fans from ventilating plants, dance bands and amplifiers,
radio sets, and various noises arising from the demolition of buildings,
pneumatic drills, compressors, etc. In all cases the Sanitary Inspector
has been able to make suggestions and offer advice which has led to the
cessation or reduction of the noise.
Atmospheric Pollution.
Investigation into atmospheric pollution in the City was continued
during the year at three sites, Mayfair, Pimlico and Charing Cross, where
deposit gauges, which measure deposited pollution, and lead peroxide
cylinders, which measure the sulphur activity, are sited. The following
tables give the results of the monthly analyses.