Nearly everyone will have suffered ən some occasion from the hiss in a water-pipe due to a distant tap which is running or leaking or to the vibrations of circulating pumps which may pass along the heating pipes and produce an unpleasant hum in all he roo. of a building.
J. E. R. Constable, of the National Physical Laboratory, has described some interesting experiments for the removal of such noises. He has found that if a length of strong rubber piping is inserted into the iron or lead piping the noises may be rendered inaudible. If the noise is a hiss, and therefore due to a vibration of high frequency, the ruber insert need not be more than a few inches long, but if itis 2 low hum, such as arises from a pump, a longer one is necessary. Constable found that in order io suppress the hum of a pump in the heating system in a laboratory it was necessary to insert three-fact &ngihs of large canyes-reinforced rubber hose into the main outflow and return pipes near the pump, Measurement showed that the inten-'y of the hum in the rooms of the oratory fell by 95 per cent. after this, During the investigation the effect of clamping rubber washers between the flanges of the iron circulation pipes was measured. The washers produced no detectable dimination in the hum conveyed through the heating system.
Text read from the printed page and cleaned; old type leaves the occasional error.