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bourhood. This compressor was in continuous operation so that
there was no respite for the residents at night or at week-ends.
The vibrations were manifested in the houses in the vicinity and
movable articles, especially suspended ones, could be seen vibrating
in rhythm with the cycle of the compressor. The effects were
also felt by residents in bed and whilst sitting in an easy chair.
Even the growing trees and garden hedges and fences could be
seen in motion on still days. The electric motor driving the
compressor also gave rise to a magnetic whine but a new electric
motor was fitted which overcame this objection. At one time
noise was also experienced from the air intake but the direction
it faced was altered and an efficient silencer was fitted. In an
endeavour to overcome the vibration the foundations of the compressor
were excavated and added to and at the same time provision
was made for isolating the foundations from the concrete
floor of the building containing the compressor and although it
was thought that there was some diminution of the vibration
transmitted to the surrounding soil it did not meet the case so
far as the residents were concerned. Further technical consideration
was given to the problem and the Company decided to
design a balancing gear to overcome the forces set up by the
reciprocating parts of the compressor. This balancing gear was
subsequently installed and very materially reduced the vibrations
transmitted to the surrounding soil. In fairness to the Company
concerned it should be noted that they appeared to spare no
expense in their endeavours to deal with these problems.
At another factory an electrically operated vertical compressor
was installed in a leah-to open sided building immediately
adjacent to the gardens belonging to houses and although this
plant was in operation only in the daytime it gave rise to complaints
of noise. The wall of the main factory building reflected
the noise in the direction of the houses. Steps taken to reduce
the noise included the fitting of a silencer on the air intake;
alteration of the direction of the air flow into the air receptacle
which it was thought would reduce resonance, insulating the
exterior of the metal air receiver also to reduce resonance; the
fitting of acoustic material at the top, back and side of the
compressor plant to absorb noise and prevent reflection; and the
provision of tarpaulins on the open side of the building to intercept
some of the residual noise. Although these steps undoubtedly
effected some improvement the residents were still not satisfied
and the Company concerned ultimately installed a lower power
compressor which with appropriate insulation measures brought
about a marked improvement. At the same factory, metal grinding
and fettling carried on in the open air or partially open
space also gave rise to complaints and it is hoped that the
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