The start of April signals the beginning of spring and with it thoughts of spring cleaning. Dirt accumulates every where, of course, but in the bell chamber there is more than you would expect. No, the pigeons have not broken in again. The netting we fitted is quite effective, though they nest just outside and so the odd bit of debris blows through. Pigeons are blamed for the mess in many bell towers, but having banished them, we now have to contend with a source of dirt that may surprise many people.
You have heard of noise polllution, a term of abuse very fashionable for describing sound which one does not like made by someone else. What you may not have realised is that very high levels of sound can actually lead to a kind of fall out. You may remember from school physics that rain is caused by particles of water vapour fusing together to form progressively larger droplets. While the smaller particles can float indefinitely in the air, the larger drops can’t and fall as rain. What puzzled scientists far a long time was what made the droplets bump into each other hard enough to stick together. In fact there is violent turbulence inside clouds which does the trick and it is no accident that when thunder and lightning are added, the process is more violent still and the rain drops are formed faster and are very large.
It is now known that a similar process takes place with dust. There is always dust in the air as any housewife or motorist knows, but most of it is very fine and stays there for a long time.
You may have noticed that there is always a lot of dust near noisy industrial sites and motorways. This is no accident. Near very intense sounds, the particles get fused together and fall out as a heavy layer of dust. You may also remember from your school days that sound intensity reduces with the square of the distance from it. In simple terms, that means that an inch from a clapper when it strikes the bell, the sound is about a million times more intense than what you hear in the church yard. As you may imagine, the more active a tower, the faster the dust falls.
Fortunately with an active tower, we also have plenty of volunteers to shovel out the dust when needed. We find that once a year is about often enough and the beginning of April seems the best time.
Gardeners may be interested to know that the nutritional value of the dust is quite high. If anyone would like a barrow load of this year’s dust, please ask one of the ringers.
John Harrison (Apr 1988)
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